Uncontrolled bushfires, sparked in September and raging since October, continue to ravage the southern and eastern parts of the continent. So far, 25 people have lost their lives, thousands of houses have been destroyed, and whole towns have been razed to the ground. Countless native animals and livestock have died. Communities are grieving.  And there are months left to go in this fire season.

While the unfolding tragedy that has captured global headlines highlights our vulnerability in a rapidly warming climate, it also exposes a gaping absence of climate leadership both in this country and globally. Communities have been left shattered, exhausted and looking for answers. As a climate scientist who has been working on these issues for decades, I share below some thoughts on how we got here and the urgent new course we need to set.

Iconic places, fragile ecosystems

This week, flames ripped through landscapes that I had spent my youth exploring. Land that has been nurtured by indigenous stewardship for millennia. Places like the Wollemi, the Blue Mountains, Kosciusko, Namadgi, Wombeyan and the Budawangs. If you aren’t familiar with these places, look them up.  They are–or were–stunning examples of the planet’s unique cultural and ecological heritage.

As a teenager, I walked in dense old-growth rainforest with plant species that had survived from Gondwana. I swam in creeks and streams cascading off sandstone escarpments. And I marveled at aboriginal cave art that had existed for thousands of years. Many of these jewels may now be lost for future generations.

In addition to these irreplaceable sites , some of the planet’s most unique species live only in Australia. To date this season, an estimated one billion animals have died in the fires. These include many of our marsupials–such as koalas, kangaroos, wombats and bandicoots–  as well as reptiles and countless bird species.

Some of these native fauna may now be on the brink of extinction. Even those lucky to survive the fire front will likely perish because the ecosystems on which they depend may be struggling to recover for years and may never succeed. A burnt landscape offers little in the way of water, food and shelter. Across the country, decades of conservation efforts have been  undone by these unprecedented firestorms.

And on top of all this is the desperate human tragedy.  People lost their lives defending their homes. Others were engulfed in flames while fleeing to safer ground. A firefighter was killed when a terrifying wind rolled a ten-tonne fire truck. And several elderly people living on their own were not able to evacuate from their properties. Entire villages have been scorched  off the map. In towns across the country, people are choking on smoke-filled air. Major cities like Sydney, Melbourne and Canberra are cloaked in haze and red sunsets, with residents dealing with serious reductions in air quality for weeks on end.

Part of my decades-long role as a climate scientist has been to explain to people what’s at stake if we fail to protect our climate.  Over the years, I have produced journal articles, reports, infographics, and videos warning of impending climate impacts. I’ve spent time walking the U.S. halls of power, attending meetings on Capitol Hill and in state legislatures to suggest innovative and effective solutions. I’ve given interviews and speeches on how little time we have left to de-carbonize our energy sources before our planetary life systems start to fail.

In all this, I’ve found that words are useful . But nothing we scientists have done could wake people to the climate threat the way that seeing the places you know and love  destroyed has done. And having to tacitly acknowledge that we all have played a part in that.

A kangaroo stands on ground blackened by a bushfire near Coonabarabran, about 350 km (217 miles) northwest of Sydney January 19, 2013. REUTERS/Josh Smith

Hot and dry

In the three months since October, an area the size of Tennessee  has been left a blackened wasteland in the most intense fire season on record. Images of the Australian continent from space show plumes of smoke across the whole southeastern coast. In addition, the smoke haze is currently blanketing parts of New Zealand, more than 1200 miles to the east across the ocean. The smoke is even reaching across the Pacific to South America. Firefighters have arrived in Australia from Papua New Guinea, New Zealand, the UK, Canada, and the US, with other offers of assistance from France and Singapore.

Our fire season is starting earlier, lasting longer and taking an increasingly catastrophic toll. There are months yet to go in this one.  We are truly living through a climate emergency.

Earlier this week, the Australian Bureau of Meteorology declared 2019 our hottest and driest year on record. Our annual mean temperature in 2019 was almost 3°F above average, and our average rainfall was 40% below normal. These were both key factors influencing current fire conditions across the country. Aussies are not unfamiliar with fire seasons by any means, but climate change is supercharging these fires. They are now deemed to be in a new category called “catastrophic” by the fire authorities. Last year, former fire chiefs issued a warning that the country was not prepared for the kinds of conditions projected, but their concerns were rebuffed by the current administration, led by Prime Minister Scott Morrison.

Many Americans have been shocked by the sheer scale of the fires in Australia. Australia is a big country–roughly as wide and tall as the contiguous United States . These current fires in the southeast of the country cover an area about a hundred times the size of last year’s CA fires  and around twelve times the area of the CA fires the year before that.

As we’re not even halfway through our summer here, with dry summer heat to endure yet, there is little hope of containing these fires.

Annotation of a Jan. 4 image from NASA’s Aqua satellite shows the areas affected by wildfires at that time. Credit: NASA/EOSDIS/LANCE/GIBS/Worldview/Joshua Stevens

Climate denial

To the rest of the world, I cry “This is what climate inaction looks like.” 2019 was the second hottest year on record, globally, as announced just this week. The six hottest years ever recorded are now the last six. In this warming world, Australia’s climate is trending in a terrifying direction. Yet, Australia is one of the world’s highest emitters of carbon pollution, per capita, as well as the world’s largest exporter of coal. Our emissions reporting would triple if we took account of our exports.

But the conservative political elite in Australia still refuse to support any meaningful action on climate.

If they stopped there, it would be gross negligence on a global scale. But it’s worse.

In the face of unequivocal evidence linking global warming to increased climate impacts including bushfires, we have a leadership that  misleads and deceives to maintain the status quo. A leadership that pumps out denial memes and shirks our global responsibility as an industrialised economy.

They do this for profit: their ties to the fossil fuel industry are strong. And they have help: the machine of Rupert Murdoch’s enormously powerful media empire. His organisation continues to spread lies and climate denial in our national media.

This week, one of its own employees at The Australian newspaper resigned, slamming their dishonest coverage of the bushfires that downplays the role of climate warming. This week, the paper is peddling the line that arsonists were largely responsible for the ignition of these fires, a claim that has been flatly refuted by police.

The Australian government continues to assert – most recently at the COP meeting in Madrid–that we are an insubstantial player on the world stage, responsible for a mere percentage or two of global emissions and thus our emission reductions would make little difference. But this argument is an immoral cop-out .

When it suits the Australian government, we are proud to “punch above our weight”. We proudly followed the British into multiple wars, we were a founding member of the United Nations, we even claim to be a world leader in protecting whales. Strange that we took on those roles, given we only have a measly 0.3% of the global population. At the climate negotiations, our government’s lack of leadership has branded us an international pariah.

The vast majority of the thousands of Australian firefighters battling the country’s bushfires are volunteer. Several have lost their lives this season.
https://www2.dfes.wa.gov.au/_layouts/images/DFES.SPS2010.Website/Fire.jpg

Ways forward

But in a scorched Australia, this morally bankrupt stance of climate science denial and climate policy negligence will have little traction anymore. We are at a turning point in public opinion. These fires have shaken us awake. Australia’s climate has changed forever. The public mood here is one crying out for real leadership and a path forward. We can no longer put up with vacuous and irresponsible tropes from a government beholden to fossil fuel cronies. There is clearly an alternative path.

Australians understand the enormity of what we face. It is clear we need to de-carbonise as a major priority. We know this must be a global effort to achieve that goal. And as we struggle to keep our precious lands from burning, we see that this action must be on nothing less than a war footing. Because that is the scale of what we are dealing with.

Inaction is not an option.  We cannot afford to lose the country  that we rely on, that we are a part of, that we owe our existence to.  To save this beautiful land–and ourselves–we will need to innovate, to build resilience, to change our ways and to fight like there is no tomorrow. Our time is now. And Australians are already marching in the streets.

Protesters demonstrate against the Australian government’s inaction over climate change despite the bushfires crisis, outside the Australian Embassy in London, Britain, January 10, 2020. REUTERS/Henry Nicholls

According to NOAA, “The January–October combined global land and ocean average surface temperature was the warmest such period on record, surpassing the previous record set in 1998 and 2010.”

This visualization shows how global temperatures have risen from 1950 through the end of 2013. Source: NASA/GSFC, GISS

Nine of the ten hottest years on record are since the year 2000

Over the last half century, global average temperatures have continued to climb. Here are some astounding statistics:

• Nine of the world’s top ten warmest years have occurred since the year 2000
• There has not been a monthly cold record set since 1916
• October was the 356^th month in a row with global average temperature above the 20^th century average
• 2014 will be the 38^th consecutive year above global average temperature

This means if you are a young person in your 30s you have never experienced an average year, but have spent your whole life in a warmer world.

Temperature trends continue to climb. Source: NOAA

Years in which El Niño amplifies warming are usually the hot ones – not this year

However, 2014 is different from other recent record-breaking years. So far, it is happening without the influence of an El Niño event, which usually brings warmer weather. The warming of the tropical central and eastern Pacific Ocean during an El Niño affects weather in many parts of the world, and was present during the scorching years of 1998, 2005, and 2010 – the top three in the list. This year El Niño has not made its presence felt yet, and NOAA has lowered the odds of it happening, but temperatures still remain high – a harbinger that the paradigm may be shifting. It seems that regardless of what happens with the natural ocean variations, human-caused warming is now clearly dominating the climate system.

2014 will likely add another peak in the global temperature curve, largely as a result of warming due to heat-trapping emissions from human activity over the last half century. As the headline statement from the IPCC 5^th Assessment Report made clear several weeks ago, human activity is “extremely likely to have been the dominant cause of the observed warming since the mid 20^thcentury.”

Toward a solution

To avoid a future where we continue to relentlessly break temperature records, we need to deeply and swiftly reduce our heat-trapping emissions. The historic climate agreement last week between the U.S. and China could start us on that road.

During that week, there was a perigean spring tide – an extra-high tide when the sun, moon, and Earth are aligned and the moon is closest to Earth in its monthly orbit. This alignment happens three or four times a year. In many locations along the U.S. east coast, these extra-high tides – colloquially known as “king tides” – brought flooding last week to places like the Florida Keys, Charleston, Annapolis, and Washington DC. These events give us a glimpse into the future, as I outlined in an earlier blog on king tides.

Floods will vary in magnitude, and some communities will be better prepared than others. However, the large number of such events and their growing duration and extent has the potential to cause deep disruption, as is already the case here in Broad Channel in Jamaica Bay, NY. Credit: Peter Mahon/West 12th Road Block Association

Our analysis shows that this kind of tidal flooding could become the new normal in many places in the next 15 years under a global sea level rise of about 5 inches by 2030 and 11 inches above today’s levels by 2045. (You can find the technical background study outlining the mid-range scenario we used here. For news coverage of our report, see articles here, here, and here.)

NOAA studies have shown that in several communities, nuisance flooding now happens four times more often than it did just 40 years ago. In the next 15 years, two-thirds of the communities we analyzed could see a tripling or more in the number of high tide flood events each year.

Of the 52 locations we examined, 30 (shown here) can expect at least two dozen tidal floods per year, on average, by 2030.  By 2045, one-third of the locations we analyzed can expect 180 or more tidal floods per year. And nine locations could average 240 or more tidal floods a year by 2045. Credit: UCS Encroaching Tides Report 2014

The case study of Jamaica Bay, New York

We know that many places are already on the front line of tidal flooding – places like Jamaica Bay, New York, which we profile in the report. Over the last century, the water level in Jamaica Bay (as measured at the nearby Battery tide gauge) has risen nearly a foot, owing to both global sea level rise and local changes. Minor flooding events in the Broad Channel area now occur once or twice a month, or more. And our analysis shows that continued sea level rise means that the frequency of flooding events in Jamaica Bay will triple by 2030, and increase nearly 10-fold by 2045, compared with today.

Dan Mundy, Sr., former president of the Broad Channel Civic Association and a retired captain in the New York City Fire Department, knows that flooding is becoming worse. “Every home in Broad Channel has a calendar with the lunar cycle and tide predictions clearly marked for each day of the year,” he says. “We live by the tidal cycles here: flooding is becoming more common, and much more of an inconvenience than ever before.” Volunteer firefighters at the Broad Channel Fire Department know which streets might need evacuation by inflatable boats.

The Broad Channel community is a proactive one. After more than a decade of lobbying by the Broad Channel Civic Association, the City of New York has funded and begun work on a $23 million project to enable West 11th, 12th, and 13th Streets to withstand and avoid flooding. Measures to make critical services more resilient, including the power supply, wastewater treatment, health care, and transportation, are also under development. The communities of Jamaica Bay—with partner agencies and organizations—are charting a path to urban coastal resilience that others around the country can build on.

In the long run, we will need more concerted action to avoid the worst impacts of sea level rise by ultimately reducing our heat-trapping emissions. But in the short term, the many other communities that will join the front line of tidal flooding will need to learn from the experience of Jamaica Bay and be able to adapt and response to the rising tides.

The USA national team huddle in the rain before the start of the World Cup soccer match between the USA and Germany in Recife, Brazil, yesterday. Source: Ricardo Mazalan/Associated Press

In less than 24 hours, the city was drenched by almost 4 inches (100 mm) of rain – a quarter of the monthly average rainfall in a single day. Downpours that lasted for three days also affected the opening match in Natal less than two weeks ago. The World Cup coverage has been accompanied by a multitude of posts on “biblical” flooding (see here, here and here).

We know heavy rainfall events are becoming more common globally and projected to increase in frequency in the future.

In fact, right now back here in the U.S., we are encountering ongoing flooding in the upper Midwest after days of rain. St Paul has declared a state of emergency; levees in Newport, a small town in Minnesota that lies along the Mississippi, are in “terrible condition” and only feet from being breached; Sioux City, Iowa, is experiencing its wettest month ever; and more than a fifth of Wisconsin’s corn crop is in poor or fair condition after drenching rain.

The U.S. National Climate Assessment clearly states that heavy downpours are increasing across the country, especially over the last three to five decades: “The heaviest rainfall events have become heavier and more frequent, and the amount of rain falling on the heaviest rain days has also increased.”

Since 1991, the amount of rain falling in very heavy precipitation events has been significantly above average. This increase has been greatest in the Northeast, Midwest, and upper Great Plains – more than 30% above the 1901-1960 average. Source: U.S. National Climate Assessment 2014.

In a future of more rain and increased flooding, emergency response and disaster preparedness will be forefront on our radars. The challenge is for the U.S. to show leadership and be emergency responders for the global issue that is here with us now — most importantly by reducing our emissions and providing adequate resources to the task at hand. That’s why the president’s proposed resilience fund – that would help communities prepare for climate change and could reduce the need for costly bailouts in the future – is so important.

Henry Paulson, former Secretary of the U.S. Treasury, agrees. This week in the New York Times, Paulson wrote some wise words about the climate crisis: “There is a time for weighing evidence and a time for acting. And if there’s one thing I’ve learned throughout my work in finance, government and conservation, it is to act before problems become too big to manage.” Hear, hear.

Sea ice – the frozen crust of the ocean that grows to about 3 feet thick in a season – begins to grow in the autumn and peaks in early spring. Now, I’ve written earlier blogs about why summer sea ice decline should be front page news and the role of the Arctic in climate. So what’s up with winter? The peak this year was low again, despite a late season surge of growth in March. In fact, winter sea ice extent in the Arctic has been below average every winter for at least the last decade, as you can see on this interactive graph.

Sea ice decline is shown dramatically in an animation screened recently at the American Association for the Advancement of Science (AAAS) meeting in Chicago.

The amount of multi-year sea ice in the Arctic has declined over the last 25 years. The bright white ice is the oldest thickest sea ice. Source: NOAA/Climate.gov and Mark Tschudi, CCAR, University of Colorado.

Winter sea ice decline should also be front page news. Of more significance than the areal extent is the fact that the Artic is losing old and thick sea ice. Old sea ice is generally much thicker than young sea ice, and thus contributes more overall to the total volume of the Arctic ice pack. Think of it like ice cubes in your drink. If you have a glass with deep ice cubes floating at the top, your drink will stay cooler longer and the ice will take longer to melt. If you have very shallow ice cubes floating on the top that nevertheless cover the same area, they will melt quicker simply because there is less ice volume.

In the 1980s, about 25% of the Arctic sea ice was estimated to be multi-year ice older than 4 years – but this year around 7% is that old. Younger and thinner sea ice is far less likely to survive the warmer summer. Source: NSIDC, and M. Tschudi, University of Colorado

Younger and thinner sea ice is far less likely to survive the warmer summers, just like slim ice cubes in your drink melt out quickly. For thousands of years, Arctic sea ice has built up in the winter and decayed in the summer, but not all of it melted out each year.

The ice that survives the summer is added to during the next winter, forming what is known as “multi-year” sea ice, which can reach more than 12 feet thick and can be over five years in age. But the dramatic decline of summer sea ice in the Arctic over the last decade has led to a decrease in multi-year thick ice.

In the 1980s, about 25 percent of the Arctic sea ice was estimated to be older than four years in age. But for every year since 2008, less than 10 percent of the sea ice in the Arctic is older than 4 years.

The Arctic is now an ocean of rapidly melting thin ice cubes.

Each year, the amount of CO2 in the atmosphere rises during the northern hemisphere autumn and winter, then decreases through the spring and summer as plant growth removes the CO2 from the air during the growing season. The annual peak usually occurs in May, but this season we will experience this new milestone of 400ppm CO2 for a couple of months before the annual decline occurs. Source: Scripps Institute of Oceanography.

The excess carbon that you and I have been dumping into the atmosphere for the last half century — from deforestation and from burning coal, oil, and natural gas — has pushed CO2 levels more than 25% higher than when measurements of air began at Mauna Loa in the late 1950s. These critical measurements by the Scripps Institution of Oceanography represent the longest continuous monitoring of CO2 in air. However, facing a funding crisis, Scripps has astoundingly had to resort to crowdsourcing to make up the shortfall in federal funding. They are one of only two agencies that carries out measurements at Mauna Loa (the other one being NOAA, that began monitoring about a decade later than Scripps).

Carbon dioxide (CO2) concentration in air at the Mauna Loa observatory in Hawaii has increased by more than 25% since measurements began in 1958 — when levels were at 317ppm. Today they have topped 400ppm. Source: Scripps Institute of Oceanography.

As I’ve described in an earlier blog, my scientific career began in a 350ppm world. And, now in our 400ppm world, we need a world-changing view to tackle the challenge that we face. We must reduce global emissions of carbon, by transforming both how we produce energy and how we choose to live going forward. What is required of us is enormous but I believe we are up to the task — after all, the 450ppm world is fast approaching.

Featured image courtesy of Flickr user Sharloch.

1. Young people are simply not living in the same climate their parents grew up in: The year 2013 was the 37th year in a row that global average temperature was above the 20th century average. Each of the last three decades has been warmer than the one before. Across the US, warm temperature records are being broken twice as often as cool temperature records.

2. Over nine tenths of the excess heat from global warming is going into the ocean: The increase in the amount of heat stored in the ocean over the last 30 years is enormous – it is equivalent to the amount of energy from a bomb the size of the one dropped on Hiroshima being released every second for thirty years. A warmer ocean expands and results in sea level rise. This heat will eventually be released from storage over decades and centuries to further warm the atmosphere.

Source: Skeptical Science

3. Ocean acidification is occurring, transforming marine ecosystems: Carbon dioxide emissions are not only leading to warmer oceans and other climate disruptions, but our oceans are absorbing a quarter of this excess carbon dioxide from the atmosphere, leading to a more acidic ocean (lower pH levels). Ocean acidification not only affects sea creatures, but everything else that depends on them in some way, from food and habitat to tourism and local fisheries.

Source: PMEL NOAA

4. The amount of carbon dioxide in our atmosphere is unprecedented in human history: Last year, levels of carbon dioxide in the atmosphere reached 400ppm (parts per million) for the first time since humans walked the planet. Over the last decade, this rate of change is faster than at any time in the recent geological record. This faster pace makes it more challenging for species and natural systems to adapt.

Tonight’s Senate action is a reminder to all of us why this is an extremely important conversation not only for the United States but for the world. Together, we urgently need to reduce our global carbon emissions.

The aftermath of typhoon Haiyan. Source: Oxfam

The United Nations Framework Convention on Climate Change (UNFCCC) states its objective is to stabilize emissions “to prevent dangerous anthropogenic interference with the climate system.” This oft-quoted phrase takes on a new dimension as we see the aftermath of one of human history’s most powerful storms, with sustained winds of almost 200 miles per hour and waves up to 30 feet high wreaking havoc on hundreds of local communities.

It is clear that human influence has been the dominant cause of our warming climate over the last half century. If the global ocean and atmosphere continue to warm from unchecked emissions, our future will likely be marked by more intense typhoons and hurricanes equal to the strength of Haiyan and Sandy. It’s also clear that if we are to stay within the carbon budget necessary to keep climate impacts from becoming unmanageable, we will need to decarbonize and leave fossil fuels in the ground.

Balancing our budget

The global carbon budget is the estimated amount of total carbon we can dump into the atmosphere and still have a reasonable chance of avoiding “dangerous” climate change. The “dangerous” temperature level has been pegged at a warming of 2°C (3.6°F) above the pre-industrial global average temperature. However, many would argue this temperature limit should be lowered in light of the impacts we are already seeing, as discussed in a recent UCS blog here and in the latest UNEP report on the Emissions Gap. As a benchmark, the difference in global average temperature between an ice age and an interglacial (a warm period) is only about 5°C, so a 2°C temperature increase is significant.

Source: University of Cambridge, Program for Sustainability and Leadership

The total amount of carbon that would take us to this level of warming has been estimated at 1000 billion tonnes of total carbon starting from the Industrial Revolution. We’ve already spent half of that budget – see the University of Cambridge’s full infographic here.

Of course, the impact of spending our entire carbon budget depends to some degree on the assumptions made about how the earth’s system responds, but most estimates using the 2°C threshold agree that we are about halfway through our allowance.

The Intergovernmental Panel on Climate Change (IPCC) explains that we may blow our entire carbon budget in the next 30 years or so at the rate we are going. But if you read the fine print, the carbon budget proposed by the IPCC doesn’t even give us a sure guarantee of staying below the 2°C threshold – it only gives us a 2 in 3 chance of doing so. Not great odds.

Another way of visualizing the carbon budget is to show an estimate of the remaining reserves that we need to leave in the ground. The amount in the ground is truly massive compared to what we have already used. The design website “Information is Beautiful” has an infographic that uses data from the International Energy Agency, NASA, NOAA, and the World Bank to show the current overall balance. It’s sobering. By their estimates, if carbon emissions continue to increase at 3 percent a year – as they have been – the point where we break our 2°C carbon budget limit is a mere dozen years away. (See the full version here.)

Source: Information is Beautiful

Carbon dioxide may be colorless and odorless and seemingly benign, but it is long-lived and the most powerful heat-trapping emission from human activity. Two-thirds of the carbon dioxide you and I produce today from burning oil and gas in our cars and for our electricity will still be around in the atmosphere in a hundred years – it takes that long to be naturally removed. It is past time to give up our fossil fuel addiction and instead focus on balancing the ecological budget. Whether we exceed our “safe” carbon level in ten years or forty years really is up to us.

As the Philippines lead negotiator Naderev “Yeb” Saño so poignantly requested on the opening day, let’s hope the talks in Warsaw do reach a “meaningful outcome.” Saño’s hunger strike, in solidarity with the millions affected in the Philippines, has now spread to some participants at the Warsaw COP19 meeting and to wider civil society around the world. With the Philippines now faced with thousands of people dead and millions homeless, Saño implores us to act. Collectively, we must step up to the challenge of tackling this immense global crisis.

Smoke from a 200-mile fire front west of Sydney blankets the city. Image: Rex/Phil Hillyard/Newspix

Right now there are more than 60 fires blazing in the state of New South Wales, where one in three Australians lives. Temperatures are forecast to reach almost 100 degrees F with wind gusts over 60 miles per hour. A fire front almost 200 miles wide is threatening western Sydney.

The authorities have declared a state of emergency, with the situation into its sixth day with little sign of abatement. The Bureau of Meteorology has issued warnings this week that are typical of mid-summer, not spring. And for my parents, they just don’t recall spring conditions like this before. It’s like watching the weather on steroids.

Australia bracing for extreme fire season

This is the second time this year that the Australian wild fire rating system has risen to “catastrophic,” a designation that was used for the first time during the 2009 Australian fire season. The country has just had its warmest 12-month period on record, its warmest September on record, and has just come out of an exceptionally dry and warm winter.

Similar to conditions the U.S. Forest Service and other emergency responders were facing in the northern hemisphere this spring, Australia is facing a tumultuous start to the southern hemisphere fire season.

The Australian bush fire danger rating scale now includes “catastrophic”. Source: NSW Fire Service

Fire behavior unprecedented

Fire seasons, of course, have great variability from year to year, but both in the U.S. and in Australia experts are saying the fire behaviors they are seeing are unprecedented.

In the western U.S., fire season is now two months longer than it was 40 years ago. According to the U.S. Forest Service, wildfires are increasing in frequency, intensity, and complexity. Wildfires are twice as large and three times more expensive as they were a decade ago. This past summer saw extreme and unprecedented behavior of fires in Colorado and California. The science is clear that humans have influenced global temperatures over the past half century. And the latest IPCC report states “future warming of extreme temperatures is virtually certain.”

Extreme temperatures, increased wildfire risk, higher costs

The costs of fighting wildfires across the U.S. have averaged more than $3 billion per year, and home protection contributes substantially to this amount. Nearly one-third of what the Forest Service spends each year to fight forest fires goes to resources and manpower to protect homes and structures, equating to more than $1 billion per year. The U.S. Forest Service is increasingly being strapped for funds as the wildfire seasons now lasts longer than it previously did and more people are building homes near forests.

A recent forest study in Oregon showed when the average summertime temperature is just one degree Fahrenheit warmer, the cost of defending these homes doubles. Over the last several years, the Forest Service has used money meant for recreation and land management programs to fight fires. Decades ago, about 20 percent of the forestry budget was devoted to fire. But this last fiscal year, more than half of the U.S. Forest Service budget was spent on fighting wildfires.

With climate change now part of our daily lives, we are witnessing the beginnings of a very challenging problem for emergency managers. It is playing out for us in Australia today.

Over 60 bush fires are blazing in the state of New South Wales, covering many areas with thick black smoke. Source: NSW Rural Fire Service

While this is shocking and part of a several-decade decline in Arctic sea ice, what’s also alarming is the lack of substantive media coverage. The decline in Arctic sea ice should concern all of us in the same way that a collapse of the economic system does. It deserves front page billing. A recent Nature commentary stated that “the costs of a melting Arctic will be huge, because the region is pivotal to the functioning of Earth systems such as oceans and the climate.” They don’t mince their words.

Not only has the extent of sea ice been declining since satellite measurements began in the 1970s, but the volume has also decreased dramatically. The volume of Arctic sea ice in August 2013 was less than a third the volume it was in August 1979. Source: Andy Lee Robinson

Here are five reasons why the decline of the Arctic sea ice matters:

1.  Sea ice reflects sunlight, keeping earth cool

When bright, reflective sea ice melts, it gives way to a darker ocean. More heat is absorbed by a darker surface, leading to more warming. This is known as the ice-albedo feedback effect. Largely due to the recent dramatic loss of sea ice and this feedback, the Arctic is now warming at twice the global rate.

2.  Sea ice forms a surface barrier, moderating winter weather

Sea ice covers the ocean for much of the year, impeding the transfer of heat and moisture from the ocean to the atmosphere. With less sea ice extent and thinner sea ice becoming common, there is a greater transfer of both moisture and heat to the atmosphere in the Arctic. Combined with the ice-albedo feedback, this amplifies the region’s warming, and may affect circulation patterns like the jet stream, that can affect weather patterns in the lower 48 states and elsewhere.

3.  Sea ice influences the ocean conveyor belt

As sea ice forms in the Arctic and Antarctic, dense salty water sinks to the bottom of the ocean starting the “global ocean conveyor belt” that pumps heat and salt around the world’s oceans. The flow of this water helps regulate temperature and distributes nutrients throughout the oceans. It is crucial to the oceanic food chain and takes hundreds of years to complete a full circuit. The “conveyor belt” helps keep places like London temperate even though they are further north than much colder cities like Boston.

4.  Indigenous communities rely on sea ice for their culture and livelihoods

For many indigenous communities sea ice affords protection from waves and coastal erosion, provides a surface for distant travel, a habitat for birds and animals they hunt, and forms a central part of spiritual beliefs. The ecosystem services from sea ice that indigenous communities depend on are diminishing.  Along with that, the world is losing the expert knowledge and the physical locations of cultures with an intimate connection to the Arctic.

5.  Sea ice affects both land-based and ocean-based ecosystems

The ecological consequences of changes in Arctic sea ice are outlined in a recent paper in Science here. Sea ice determines the interaction between marine and terrestrial species, influences ocean productivity, and affects local weather. From phytoplankton at the base of extensive food chains to potent heat-trapping methane release from permafrost, changes to natural systems will come at great financial and ecological cost.

The decline of the Arctic sea ice. Source: NSIDC 15th September, 2013

Loss of Arctic summer sea ice – not “if” but “when”

As the relentless decay of sea ice continues, an ice-free summer in the Arctic is a given – it’s now a matter of “when,” not “if”. Nine of the lowest years on the satellite record for Arctic sea ice minimum extent have been in the last decade. But we do have a choice – we must act swiftly to reduce emissions and ensure we avoid the very worst impacts to the fragile Arctic ecosystem. We can and must try to delay the disappearance of summer sea ice and time is of the essence.

Front page image courtesy of  Richard Petry.

In the last IPCC report in 2007, the sea level rise projections listed in the summary document did not include the full estimated contributions from changes in ice flow and melting of the two great ice sheets on the planet, Greenland and Antarctica. This led to erroneous speculation in media coverage that the projected sea level estimates were lower than previous reports. Hopefully the forthcoming report will be more explicit about all of the contributions to sea level rise – the fact is, snow and ice are rapidly melting and raising sea levels.

Snow and ice – a barometer of Earth’s climate

In the last two decades I’ve seen with my own eyes the rapid disappearance of many of the planet’s snow fields and the retreat of alpine glaciers. Unfortunately, my anecdotal observations are backed up by data and are clearly linked to global warming.

Over the last century, in the Sierra Nevada the surface area of glaciers has been decreasing and spring river runoff is lower. In Montana’s Glacier National Park over the same period the number of sizable glaciers has dropped from 150 to less than 25. In Wyoming, the 44 extant glaciers in the Wind River Range have decreased in area by almost half in the last four decades. And it’s not just confined to North America. Glaciers are in retreat worldwide – in Switzerland, in Peru, in New Zealand. If snow doesn’t endure through the summer, glaciers simply cannot grow. Snow needs to remain for multiple seasons for it to form into ice and become a moving glacier.

The disappearance of land-based snow and ice

Thermal expansion of the oceans now takes a back seat to the contribution from melting of land-based ice (which was not accounted for in previous projections of future sea level rise). Source: UCS (after Church et al., 2011)

What happens to our snow fields, our alpine glaciers, and our ice sheets truly matters. The melting and retreat of northern hemisphere snow and ice due to global warming is a concern for two major reasons. The first is that when land-based ice melts, sea level rises. The second is that removing snow and ice cover on land leaves behind a darker surface which increases the amount of sunlight that is absorbed at earth’s surface – a feedback that increases the original warming.

When land-based ice melts, sea level rises

For most of the last century, thermal expansion from simply heating up the ocean was the main contributor to the global rise in sea level. But that’s changed in the last two decades.

A recent study shows melting of land-based ice and the resulting runoff into the sea now accounts for twice as much sea level rise as thermal expansion does. More than half of the contribution from land-based ice is from melting of alpine glaciers and ice caps, while Greenland and Antarctica (both ice sheets) account for the rest.

NASA satellite images show the changing extent of snow and vegetation for the globe over the course of the year. The greatest seasonal changes occur in the northern hemisphere. To persist, alpine glaciers and ice sheets need snow to accumulate from year to year. Top left is the view looking down on the North Pole, top right is the South Pole. Source: IDV Solutions

Greenland – the inappropriately-named island that is one of only two major ice sheets on the planet (Antarctica being the other) – is also experiencing major melt events annually. In the years 2007, 2010, and 2012 surface melt area was extensive and record-breaking. This year Greenland is experiencing a melt season closer to the long-term average. Don’t be fooled by 2013, though – the Arctic is still warming at twice the pace of the rest of the globe, as noted in the recent State of the Climate in 2012 report by the American Meteorological Society.

IPCC report highlights link between warming and loss of snow and ice

The contribution to sea level rise from melting of land-based snow and ice will continue to increase while emissions and temperatures rise. Our current challenge is to reduce our emissions swiftly and deeply to avoid the worst impacts of climate change. The forthcoming IPCC report will be a stark reminder that it is time to heed the science and act. The snow-speckled meadows and the majestic peaks surrounded by glaciers are surely worth saving not only for the services they provide like water supply and habitat, but also for the sake of future generations.

Why planes fly faster from west to east – it’s the wind!

In mid-latitudes in the northern hemisphere – over most of the lower 48 states – the dominant jet stream is the Polar jet stream. It separates cold air to the north from warm air to the south, and lies five to seven miles above the Earth’s surface with winds reaching more than 200 miles per hour.

With a tail wind like that, it’s no wonder flights from west to east are faster. Flying with the jet stream can decrease fuel consumption and shorten flying times considerably. In fact, pilots seek out the jet stream to either use it or avoid it. Jet streams can be thousands of miles long and hundreds of miles wide, but we usually focus on thin bands of faster-flowing air that influence local weather patterns.

Air flows downhill from the tropics to the poles and then turns east

How does the jet stream form? Well, most of our weather occurs in the very lowest layer of the atmosphere called the “troposphere” where the air is turbulent and mixes rapidly (the Greek word “tropo” means turning). The upper boundary of this part of the atmosphere is higher at the equator than at the poles, simply because warmer air at the equator expands and takes up more room. As a result, air flows downhill from the puffed up warm air at the equator to the compressed cold air at the poles.

In the northern hemisphere as this air flows from equator to pole it is turned to the right because of Earth’s rotation. This resulting west to east flow is known as a jet stream. You can see more thorough explanations of the physics from NOAA’s National Weather Service and from Skeptical Science.

A slowed jet stream meanders like a lazy river

When the Polar jet stream slows down, the wave patterns known as planetary or Rossby waves start to meander and widen, just like a river does when it slows down in its lower reaches. The meanders form large lobes that bring warmer weather much farther north and colder weather much farther south than usual. Low pressure systems form in the southern end of the troughs – these cyclonic or inward-flowing masses of air result in convective storms, heavy rainfall events, and flooding. High pressure systems form in the northern end of the ridges – these anti-cyclonic or outward-flowing masses of air bring hot, dry weather.

The slowing of the west to east flow of the jet stream produces large meandering lobes that can stall, resulting in long periods of unchanging weather. Source: Skeptical Science

The jet stream becomes stuck, leading to extreme weather

When the jet stream slows down our weather tends to become “stuck” in either of these modes, resulting in long periods of the same patterns of weather that leads to extremes. We saw the consequences of this in June of this year when wildfires raged in the western half of the U.S. while the eastern seaboard was drenched in rain. And in October 2012 Hurricane Sandy took an unusual path through New Jersey when the large loops of the jet stream were stuck, as explained in a blog here.

A recent paper suggests the stalling of these planetary waves could have caused the U.S. heat wave of 2011, the floods in Russia and Pakistan in 2010, and the European heat wave of 2003. It’s not clear yet whether these stalled weather patterns are becoming more frequent and we won’t know until we have longer data sets. However, scientists are currently trying to figure out the most likely cause of a slowdown of the jet stream.

The uncharacteristic north-westerly path of Hurricane Sandy was influenced by a blocking ridge that developed from an unusual jet stream pattern. Source: NASA

A stalled jet stream in June this year resulted in intense dry weather in the west and downpours on the eastern seaboard. Source: NOAA National Climate Data Center

The Arctic “amplification” — a possible explanation for a stalling jet stream?

In recent years the Arctic has warmed at an alarming rate (as was predicted by models) due to strong reinforcing feedbacks in the climate system. With the Arctic warming at twice the pace of the rest of the planet, the temperature contrast between the equator and the poles has decreased. The downhill run of air from equator to pole is not as steep as it was, diminishing the strength of the jet stream and resulting in the large meandering patterns.

Jennifer Francis, a Research Professor at Rutgers University, and Jeff Masters from the Weather Underground explain why this amplification of warming in the Arctic might be an explanation for a weakening jet stream. With her colleague Stephen Vavrus, Francis has also published a paper on the topic. There are other explanations that also consider changes to the heat content of the Arctic ocean as well as the role of increased water vapor transport in the atmosphere, as discussed in an American Geophysical Union blog with Kevin Trenberth. Scientists are still working on the details, but plausible explanations of this “wacky weather” are starting to emerge.

In an important step on climate action, President Obama put forward a plan that would allow him to keep his Copenhagen commitment to reduce U.S. carbon dioxide emissions to 17 percent below 2005 levels by 2020. (Read further UCS analysis of the speech here.)

But is that enough? From a scientific perspective, it can be hard to say. When we look at the global amount of carbon dioxide going into the atmosphere, there are a lot of ways countries could collectively take action to bring global emissions down to zero in the long term. Ultimately, that’s what we’ll need, otherwise carbon dioxide will continue to accumulate and change our planet essentially forever. This year saw us pass 400 parts per million of carbon dioxide in the atmosphere for the first time in human history. For many scientists, it was a sobering milestone.

“Tapping” the brakes on climate

The president compared his plan to “tapping the brakes” on a car before coming to a complete stop. That’s a good way of thinking about it and in the context of our global carbon goals, it’s an accurate way to characterize the limits of what the president can accomplish on his own under existing law. Obama’s speech is an indication that this Administration is willing to press a little harder on the brakes than it has in the past. When a new driver comes into the Oval Office, he or she will have to do more to complete the braking, too. But if we don’t do more in the short-term to reduce our emissions we’ll be left with a stark choice: slam on the brakes in ways that could harm our energy security or lock in much higher levels of warming.

The president also used this event as an opportunity to educate the U.S. public on the importance of this inter-generational issue, to highlight the severity of the impacts we are already seeing domestically, and to emphasize the need for the U.S. to return to the international arena to encourage action on climate. However, this historic commitment has to be just the beginning of the aggressive emissions reductions we need to achieve globally in all sectors. As the president noted, “science, accumulated and reviewed over decades, tells us that our planet is changing in ways that will have profound impacts on all of humankind”.

The global carbon budget and the 2°C limit

Carbon emissions are currently increasing globally by about 3 percent per year, and show little sign of slowing. The global recession was nothing more than a minor speed bump to these increases. In a similar way to considering a personal spending budget, the cumulative amount of carbon emitted over time represents our carbon budget. Some estimates suggest globally we have an allowance of roughly 1000 gigatons of carbon from the year 2000 to mid-century if we are to have a 75 percent chance of staying below a 2°C (3.6°F) warming threshold. International negotiators have recognized 2°C above the pre-industrial global average temperature as a level of warming we should stay below to avoid “dangerous” interference with the climate system.

Estimates from a National Academies of Science report in 2010 and a World Bank report in 2012 show that the pledges from Copenhagen will likely lead to a 3°C warming.

World Bank: Copenhagen pledges head for 3°C and beyond

A report last year by the World Bank made it clear that emission reductions need to be swift and deep. Their analysis showed that, even if the pledges made at Copenhagen were all met,  the world is still likely on a pathway to well over a 3°C warming. In addition a report from the National Academies of Sciences in 2010 shows we have already committed to a 1°C warming from current emissions.

So – can the U.S. pledge of a reduction in emissions of 17 percent below 2005 levels by 2020 get us to where we want to go? Not on its own. But it is a powerful message that this country is finally taking the issue seriously and returning to the international negotiations with as much good will as possible in light of the hamstrung U.S. political climate.

Earth’s global average temperature has already risen by 0.8°C since the late 1800s, so we have a little over a degree of wiggle room. However, at current rates of emissions, Earth’s 2°C carbon budget will be entirely spent by the middle of the 2020s, about a decade from now. Without stronger actions, scientists are telling policy makers that we will blow past that goal. And it may be that this goal needs to be lowered, as some have argued for a 1.5°C goal based on serious impacts appearing at temperatures increases below 2°C.

Nevertheless, we now have a commitment from the president which, if implemented, will start “tapping the brakes” on our carbon emissions relative to 2005 emissions. It’s a start, but we also need to recognize that there’s no “emergency brake” for climate change. The ambition of what our political leaders are suggesting still puts us at grave risk.

A refresher on why the tides happen when they do

Predicting the height of the daily tides at a location is not a trivial task. Tides are a complex interplay of (i) the gravitational attraction and rotation of the Earth, sun, and moon, (ii) oceanic processes like waves and currents, and (iii) the local weather conditions. Combine the first two together and you come up with predictions of tide heights, then add the last one for a bit of randomness and you have the actual tide that occurs on the day.

Twice a month when the pull of the moon and sun on the Earth are in alignment, the ocean tides are highest – these are known as “spring tides,” in the sense of bursting forth or jumping up, and occur during the full and new moon. Spring tides are bigger than “neap” tides, which occur during the other two major phases of the month, when the moon is either in its first or third quarter.

The highest spring tide of the year happens when the orbit and alignment of the sun and moon reinforce at their closest and furthest extremes from the Earth – this is what is colloquially being called a “king tide,” although this is not a scientific term. Often the highest tides in our oceans occur in June and December because of the influence of the sun on the Earth. However, the moon’s effect plays a crucial role as well and can result in the highest tides in some places being in October. Tides are a complex and fascinating topic. You can read a good explanation of the physics here.

Today’s highest tides become the new normal with climate change

Source: New Hampshire/Maine Realtors

Extreme high tides give us an excellent opportunity to raise awareness about the impacts of sea level rise on low-lying coastal areas and areas where land is subsiding. In many places, today’s highest tides will become common water levels within our lifetimes. A UCS infographic here explains how and why.

Roughly a third of the U.S. population lives in coastal counties and is especially vulnerable to rising seas and storm surge in low-lying areas. To visualize the direct impacts of a rising ocean on these communities, initiatives around the country have been collecting photographs of extreme high tides. See some images here from New Hampshire, Florida, and New Jersey.

The Bratskellar Restaurant near Portsmouth in New Hampshire during the highest tide of the year in 2011. Low tide on the left, high tide on the right. Source: Jim Lee, New Hampshire/Maine Realtors

Climate projections show that if we continue on our current emissions pathway, by the end of the century what is now a rare water level may become typical. And we know local decision makers are already talking about how to protect communities from sea level rise by finding smart ways to lessen the risks.

But these king tides also can open up the more difficult conversations of whether we can simply adapt to the future that’s headed our way or if we need to “avoid the unmanageable” with stronger mitigation efforts. Another piece of the future story — which king tides may not capture — is the impacts that occur when any given coastal storm rides in on top of these increased sea levels.

Repository of images helps planners with adaptation

Photographs of extreme high tides are a valuable repository for planners and managers in all levels of government. The images highlight places that will become increasingly vulnerable to flooding, higher storm surges, eroding shorelines, and saltwater intrusion under ongoing sea level rise.

The Environmental Protection Agency (EPA) is helping coastal managers develop adaptation plans as part of their Climate Ready Estuaries program, and is supported by the State Department. Photographs from the king tides initiative form an important part of this work.  If you are interested in learning more about high tide photography globally, see the Witness King Tides project by Green Cross in Australia, the country where chasing king tides began in 2009.

The new report is an important precursor to both the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report, the first part of which is due out in late September of this year; and the Third U.S. National Climate Assessment, which is undergoing its review (see the draft here) before being released in 2014.

All of these publications underscore the urgency of the latest climate science and the need to act quickly in addressing one of the most pressing issues of our time — human-caused global warming.

Here are three important highlights from the new report:

1. Most of the available fossil fuels simply cannot be burned

If we are to stabilize climate this century, most of the available fossil fuels cannot be burned. Estimates in this report show we can emit at most 1,000 billion tonnes of carbon dioxide from the year 2000 until mid-century to give us the best chance of limiting global temperature rise to 2^oC (3.6^o F) above pre-industrial temperature. The nations of the world have agreed that the consequences of a 2^oC rise in global temperature are so severe for the health and well-being of humanity and systems it depends on that it is a threshold that should not be crossed. Although, this story is evolving as new science is pointing to dangerous impacts under less warming — leading some to call for a 1.5^o C limit.

However, in the first 13 years of this critical period, the world has emitted nearly 40 percent of that budget already. The rate we are emitting carbon dioxide is also accelerating, with a 2.6 percent increase just between 2011 and 2012. (See more at the Global Carbon Project here.) Stabilizing the climate within the 2^oC temperature limit remains possible, but unless we intensify our efforts this decade and beyond, the promise international leaders made in 2009 will be forever broken.

Overspend in the Carbon Budget (Source: The Critical Decade 2013)

2. The risks scientists warned us about are already happening

There is consensus that many of the climatic changes we are currently seeing are due to human activity. Some of the consequences already evident are rising seas and changing rainfall patterns.

One dramatic change is the heating of the ocean globally. Over the period 1961 to 2003, almost 90 percent of the extra heat from human-caused global warming has been absorbed by the ocean. This dramatic rise in water temperature is not only raising sea level by thermal expansion but is also affecting the chemistry and biology of the world’s oceans and affecting the hydrological cycle, impacting areas far removed from the oceans themselves. (See more at NOAA Oceans and the U.S. National Oceanographic Data Center.)

The influence of climate change on the water cycle – higher surface water temperatures and air temperatures speed up the hydrological cycle (Source: The Critical Decade 2013)

3. Scientists know more about abrupt and irreversible changes

Scientists are improving our understanding of abrupt and irreversible changes in the climate system, known as tipping points. The most concerning of these are the melting of the world’s great ice sheets, shifts in the Indian summer monsoon, and changes to the patterns of rainfall in the Amazon basin. Many of these processes can have direct impacts on human well-being on a large scale.

The conclusion of the report is clear and repeats what was stressed in the initial report two years ago – this is the decade to begin decisively decarbonizing the economy. Time is of the essence.

Let’s do a classic “thought experiment” (it’s only classic because climate scientists have been telling this one for so many years now). Imagine you went to 100 medical experts and asked each of them to diagnose whether you had cancer or not. If 97 of those hundred confirmed your worst fears and verified that you did indeed have cancer, would you keep asking for more evidence before you did something about it?  Most people would have a hard time ignoring that kind of agreement amongst experts! Except, it seems, when the experts we’re talking about are climate scientists and the subject is the consequences of burning so much coal and oil and destroying so many tropical forests.

Less than half of the American public recognizes that scientists agree on Anthropogenic Global Warming, despite the fact that 97% of climate scientists endorse the science. Source: The Pew Center, Cook et al (ERL), The Consensus Project

The meme that “scientists don’t agree on whether humans are affecting global warming” is one that I still hear frequently from the public in my job as a climate scientist. There’s a big gap between what climate scientists know and what the public thinks. Researchers call this the “Consensus Gap“. The science is clear. But because public perception of scientific consensus is an important element for public support of action for climate change, this gap needs to be narrowed so that we can move ahead with policies to reduce heat-trapping emissions. Corporate-funded groups that spread misinformation in the media are partly to blame, as exposed in a recent UCS report about disinformation on climate science.

Looking over more than a twenty year period from 1991 to 2011, Cook’s new study finds the number of peer-reviewed papers that reject outright the scientific consensus on human-caused global warming “is a vanishingly small proportion of the published research.”  In fact, of almost 12,000 abstracts analyzed by the authors, less than 80 rejected the claim that global warming is exacerbated by human activity. That’s less than one percent. Not even one doctor out of our hundred giving us a contrarian health report on this one!

This is not the first study of its type by any means. There is no shortage of published research on the consensus of climate scientists and climate science publications when it comes to anthropogenic warming.  You can read Oreskes 2004, Oreskes 2007, Doran and Zimmerman 2009, and Anderegg et al. 2010. In addition, there are statements that verify the scientific claims about human-caused warming from 18 different scientific societies in the United States and more than a dozen national academies of science from around the world. And there are countless blogs on the topic including an analysis of over 13,000 papers by James Powell. Phew – consensus!

It’s telling that the analysis found so many papers that didn’t explicitly state whether or not human activity is causing climate change. That’s because scientists have known for so long that it is. It’s a given now, like gravity or the laws of motion. In recent years, in fact, scientists have focused much more on the consequences of climate change. Hopefully, this new analysis will help narrow the consensus gap with the public so we can start making decisions about adaptation and reducing emissions based on the science.

It’s also worth noting that Cook’s research was also conducted mostly by volunteers, with the publication costs funded by donations on social media websites. The paper is part of a new genre of publicly accessible peer-reviewed science. It is available free of charge for download here from Environmental Research Letters.

In 1958 Charles David Keeling for the first time started directly measuring the concentration of carbon dioxide in air at Mauna Loa Observatory in Hawaii as part of the International Geophysical Year. Photo: Mary Miller, Exploratorium (via NOAA)

I started my scientific life as a fresh-faced glaciologist drilling ice cores on the immense ice sheet of Antarctica. It was the early 1990s and my job (an amazing one, I’ll admit!) was to tirelessly process the ancient ice that we were bringing up from the deep drill hole. There was almost a mile of ice to analyze! This frozen archive is made from pure snow that fell on the continent tens of thousands of years ago and compressed into hard, cold ice. These ice cores, like many others since, reveal the secrets of ancient atmospheres from the air bubbles trapped within their lattice. They allow us to compare the modern atmosphere that is measured at Mauna Loa with what happened in the past.

Past atmospheres: the cycles of CO2 and temperature

I remember my excitement on seeing the cycles of ice ages pop out from our analysis. You’ve probably seen those graphs of wavy lines that show carbon dioxide dancing between a low level during an ice age and a high level in an interglacial (like the one we are in now).

For the last eight glacial cycles carbon dioxide has varied between 180 parts per million and 280 parts per million. Carbon dioxide has, in general, gone up and down hand in hand with global average temperature. When carbon dioxide is high, temperature is high; when carbon dioxide is low, temperature is low, with the leads and lags being well understood by the scientists studying these in detail. The ice core record shows this has been the natural cycle for at least 800,000 years. As a yardstick, homo sapiens has only been around for a mere 200,000 years at the very longest. Earth’s climate is very sensitive to the level of carbon dioxide in the atmosphere. But in the last two centuries of our short time on the planet we have altered the atmosphere drastically.

The cycles of carbon dioxide and temperature over the last eight ice ages show CO2 concentration varying between 180ppm and 280ppm. Carbon dioxide concentration is now at unprecedented levels in human history. Adapted from Luthi et al, 2008

Climate change: thickening CO2 blanket warms the world

At about the same time I was getting cold fingers from handling old ice, we had just passed the ominous 350 parts per million mark. Knowing what scientists knew then about the relationship between carbon dioxide emissions and temperature (see the First IPCC Assessment from 1990 here and the IPCC Supplementary Report from 1992 here), I could not imagine two decades later carbon dioxide levels would still be soaring upwards. But they are.

Carbon dioxide naturally forms a heat-trapping blanket around the earth – we can’t live without it. But our human practice over the last two centuries of digging up ancient sunlight in the form of oil, coal, and natural gas and then burning it has released excess carbon into the atmosphere.

For almost a million years, the earth cycled between roughly a two-blanket world (180 parts per million) and a three-blanket world (280 parts per million). By perturbing the atmosphere to this new level, we’ve managed to bump that up to a four-blanket world (now 400 parts per million) in a very short time. And we’re starting to feel it get hot under here.

Welcome to the Pliocene!

Scientists drill deep into the world’s ice sheets to obtain ice cores that unlock the secrets of ancient atmospheres. Photo: M Fitzpatrick

The last time the atmosphere had 400 parts per million of carbon dioxide was most likely between 3 and 5 million years ago, long before humans like us inhabited the earth. It was a geological epoch known as the Pliocene. The planet was many degrees warmer and scientists estimate sea level was about 80 feet higher.

Reaching 400 parts per million for the first time in human history is a wake up call for all of us. The science is clear. It’s high time we addressed the fundamental drivers of climate change — heat-trapping emissions from fossil fuels as well as deforestation practices which emit carbon and reduce the uptake of carbon dioxide.

If we don’t take action, in a couple of decades as we mark the passing of the next ominous milestone of 450 parts per million at Mauna Loa, there may be no returning to the climate we once knew.

The Galveston seawall

You may have heard about the devastating hurricane that hit the island on September 8, 1900, destroying the city and killing thousands of people. As a result, the residents built a seawall that now extends for over 10 miles along the seaward shore. Halfway through the week-long conference we took a tour along that very seawall. It’s an amazing piece of engineering – 16 feet deep and 17 feet high – much more imposing than I expected. As I stood looking down the gentle curved concrete, I wondered how long this wall could hold back the ocean.

A 10-mile long seawall, begun in the early 1900s after the worst natural disaster in U.S. history, extends along the coast of Galveston Island. Photo: M. Fitzpatrick

Hurricane Ike: over a hundred years later and with sea level almost three feet higher

Walking the streets of Galveston, climate impacts became more real for me. Every second person I met had a story to tell about where they were and what they were doing when Hurricane Ike hit in the middle of the night on September 13, 2008. The damage was not nearly as serious as it was a hundred years earlier. But as I imagined folks in their pajamas, grabbing children and pets and seeking higher ground, I thought Ike would have been just as terrifying.

Ike was only a Category 2 storm  when it made landfall (on a scale that goes to 5, that’s like being in the featherweight division), but the water still topped the Galveston seawall and resulted in massive flooding. Buildings throughout the city are still unoccupied. High water marks from Ike are sign-posted at several restaurants, near a street lamp and on a wall. These insignias were almost a foot above my head – and I’m not terribly short! If this was the resultant flooding at current sea levels what will it be like when the sea is even higher?

Coastal development along the shoreline of Galveston Island is already at risk from inundation during storm events. Photo: M. Fitzpatrick

Healthy natural buffers protect coastlines

View infographic

The sea along the Gulf Coast is rising faster than anywhere else in the United States. Galveston has seen a 3-foot rise in local sea level since the late 1880s, due to a combination of impacts from global warming and from subsidence of the land surface. Higher seas mean higher storm surges and potentially more damage from flooding as explained in a new UCS infographic.

During the week at the conference, we heard experts from around the world explain that traditional defensive approaches – like building seawalls and levies – may no longer be adequate. We also need healthy natural buffers – such as barrier islands, tidal wetlands, and mangroves – that contribute to stabilizing and protecting coastlines.

Communicating coastal impacts to policymakers and the public

One of the outcomes of this important conference was a recognition that scientists need to be more closely involved with policy makers. The group of 80 scientists drafted a set of key statements, with these top line messages (watch for a link to the final statement in the near future):

• Global sea level is rising at an accelerated rate overall in response to climate change.
• Current rates of sea level rise in many regions are unprecedented in the last several thousand years.
• Sea level rise will exacerbate the impacts of extreme events, such as hurricanes and storms.
• Society must learn to anticipate, live with, and adapt to the dynamics of a rapidly evolving coastal system.

To find out how sea level rise affects our coasts, here is a brief overview developed by UCS. In a blog from last week, my colleague, Rachel Cleetus, describes what steps experts from five different coastal states are already taking to address the challenges posed by rising seas and how they are increasing local preparedness.