Assessing "Dangerous Climate Change": Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature

This paper, by an international team of scientists, points out the clear and present danger that today's children may be handed a deteriorating climate with consequences out of their control. 

Dr. James Hansen

by James Hansen, Pushker Kharecha, Makiko Sato, Valerie Masson-Delmotte, Frank Ackerman, David J. Beerling, Paul J. Hearty, Ove Hoegh-Guldberg, Shi-Ling Hsu, Camille Parmesan, Johan Rockstrom, Eelco J. Rohling, Jeffrey Sachs, Pete Smith, Konrad Steffen, Lise Van Susteren, Karina von Schuckmann, James C. Zachos

We conclude that the widely accepted target of limiting human-made global climate warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above the preindustrial level is too high and would subject young people, future generations and nature to irreparable harm. Carbon dioxide (CO2) emissions from fossil fuel use must be reduced rapidly to avoid irreversible consequences such as sea level rise large enough to inundate most coastal cities and extermination of many of today's species. Unabated global warming would also worsen climate extremes. In association with summer high pressure systems, warming causes stronger summer heat waves, more intense droughts, and wildfires that burn hotter. Yet because warming causes the atmosphere to hold more water vapor, which is the fuel that drives thunderstorms, tornadoes and tropical storms, it also leads to the possibility of stronger storms as well as heavier rainfall and floods. Observational data reveal that some climate extremes are already increasing in response to warming of several tenths of a degree in recent decades; these extremes would likely be much enhanced with warming of 2°C or more.

We use evidence from Earth's climate history and measurements of Earth's present energy imbalance as our principal tools for inferring climate sensitivity and the safe level of global warming. The inferred warming limit leads to a limit on cumulative fossil fuel emissions.

It is assessed that humanity must aim to keep global temperature close to the range occurring in the past 10,000 years, the Holocene epoch, a time of relatively stable climate and stable sea level during which civilization developed.

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Doubling Down on Our Faustian Bargain

by James Hansen, Pushker Kharecha, Makiko Sato

Faust in his Study by Rembrandt

Humanity is doubling down on its Faustian climate bargain by pumping up fossil fuel particulate and nitrogen pollution. The more the Faustian debt grows, the more unmanageable the eventual consequences will be. Yet there are plans to build more than 1000 coal fired power plants and plans to develop some of the dirtiest oil sources on the planet. These plans should be vigorously resisted. We are already in a deep hole -- it is time to stop digging.

Humanity's Faustian climate bargain is well known. Humans have been pumping both greenhouse gases (mainly CO2) and aerosols (fine particles) into the atmosphere for more than a century. The CO2 accumulates steadily, staying in the climate system for millennia, with a continuously increasing warming effect. Aerosols have a cooling effect (by reducing solar heating of the ground) that depends on the rate that we pump aerosols into the air, because they fall out after about five days.

Aerosol cooling probably reduced global warming by about half over the past century, but the amount is uncertain because global aerosols and their effect on clouds are not measured accurately. Aerosols increased rapidly after World War II as fossil fuel use increased ~5%/year with little pollution control (Fig. 1). Aerosol growth slowed in the 1970s with pollution controls in the U.S. and Europe, but accelerated again after ~2000.

The rapid growth of fossil fuel CO2 emissions in the past decade is mainly from increased coal use (Fig. 1), mostly in China with little control of aerosol emissions. It is thus likely that there has been
an increase in the negative (cooling) climate forcing by aerosolsin the past decade, as suggested by regional aerosols measurements in the Far East, but until proper global aerosol monitoring is initiated, as discussed below, the aerosol portion of the amplified Faustian bargain remains largely unquantified.

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Grandparents Oppose Tar Sands

by Dr. James Hansen

Alberta tar sands are estimated to be 240 GtC (gigatons of carbon); see Intergovernmental Panel on Climate Change (2007) Working Group 3 report. That is about seven times greater than the cumulative historical CO2 emissions from oil use by the U.S. (36 GtC). U.S. oil use was 28% of global oil use for the cumulative amounts over the past 200 years. So Alberta tar sands contain about twice the total amount of carbon emitted by global oil use in history.

Yet some people argue that tar sands are not so great that we need to be concerned about their effect on climate. They argue that only about 40 GtC of the tar sands are presently economically extractable. However, if an addiction to tar sands is established, as it would be with big pipelines, you can be confident that the addiction would lead eventually to ways of cooking the oil out of most of the tar sands. Moreover, these numbers do not include the emissions from conventional fossil fuels used to mine and process the tar sands into useable fuel. Nor do they include the other greenhouse gas emissions produced by the mining and processing.

The global stampede to find every possible fossil fuel is not being opposed by governments, no matter how dirty the fuels nor how senseless the energy strategy is from long-term economic and moral perspectives. Instead governments are forcing the public to subsidize the polluters.  Continued...

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Public Perception of Climate Change and the New Climate Dice

by James Hansen^a, Makiko Sato^a, Reto Ruedy^b

Should the public be able to recognize that climate is changing, despite the notorious variability of weather and climate from day to day and year to year?

We investigate how the probability of unusually warm seasons has changed in recent decades, with emphasis on summer, when changes are likely to have the greatest practical effects. We show that the odds of an unusually warm season have increased greatly over the past three decades, but also the shape of the frequency distribution has changed so as to enhance the likelihood of extreme events.

A new category of hot summertime outliers, more than three standard deviations (3σ) warmer than climatology, has emerged, with the occurrence of these outliers having increased 1-2 orders of magnitude in the past three decades. Thus we can state with a high degree of confidence that extreme summers, such as those in Texas and Oklahoma in 2011 and Moscow in 2010, are a consequence of global warming, because global warming has dramatically increased their likelihood of occurrence.  Continued...

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The New Climate Dice

by Dr. James Hansen

Several people have asked for a referenceable version of our paper "Public Perception of Climate Change and the New Climate Dice", so we have placed the current version on arXiv, the permanent storage for physics preprints. This is the version of the paper submitted to Proc. Natl. Acad. Sci. with favorable reviews by Tom Karl and Andrew Weaver, so presumably it is the final version. In any case, arXiv is a permanent storage place of this version. You can find it at arXiv with referencing information or get a PDF from my web site or directly here.

Part A of the first figure in the paper (available as a PDF from my web site) makes clear why extreme anomalies are beginning to pop up all over the place. Summer anomalies over land are the most important, as discussed in the paper. Averaged over a decade the frequency distribution of seasonal mean temperature anomalies is shifting rapidly toward more extreme hot anomalies, and the distribution is becoming broader (greater extremes). Because the planet is out of energy balance, we can conclude that next decade the distribution will be shifted even further to the right.

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Scientific Case for Avoiding Dangerous Climate Change to Protect Young People and Nature

by James Hansen^a,1,2,3, Pushker Kharecha^a, Makiko Sato^a, Frank Ackerman^b, Paul J. Hearty^c,Ove Hoegh-Guldberg^d, Shi-Ling Hsu^e, Fred Krueger^f, Camille Parmesan^g, Stefan Rahmstorf^h, Johan Rockstromⁱ, Eelco J. Rohling^j, Jeffrey Sachs^k, Pete Smith^l, Konrad Steffen^m, Lise Van Susterenⁿ, Karina von Schuckmann^o, James C. Zachos^p

Summary. Humanity is now the dominant force driving changes of Earth's atmospheric composition and thus future climate (1). The principal climate forcing is carbon dioxide (CO2) from fossil fuel emissions, much of which will remain in the atmosphere for millennia (1, 2). The climate response to this forcing and society's response to climate change are complicated by the system's inertia, mainly due to the ocean and the ice sheets on Greenland and Antarctica. This inertia causes climate to appear to respond slowly to this human-made forcing, but further long-lasting responses may be locked in. We use Earth’s measured energy imbalance and paleoclimate data, along with simple, accurate representations of the global carbon cycle and temperature, to define emission reductions needed to stabilize climate and avoid potentially disastrous impacts on young people, future generations, and nature. We find that global CO2 emissions reduction of about 6%/year is needed, along with massive reforestation.

Governments have recognized the need to limit emissions to avoid dangerous human made climate change, as formalized in the Framework Convention on Climate Change (3), but only a few nations have made substantial progress in reducing emissions. Continued...

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Why I Must Speak Out About Climate Change

by James Hansen

This presentation in the TED series took place on February 29, 2012.  

Dr. James Hansen heads the NASA Goddard Institute for Space Studies in New York City and is Adjunct Professor of Earth and Environmental Sciences at Columbia University’s Earth Institute.  He was trained in physics and astronomy in the space science program of Dr. James Van Allen at the University of Iowa. His early research on the clouds of Venus helped identify their composition as sulfuric acid. Since the late 1970s, he has focused his research on Earth's climate, especially human-made climate change.  Link.

Silence is Deadly

Dr. James Hansen

The U.S. Department of State seems likely to approve a huge pipeline to carry tar sands oil (about 830,000 barrels per day) to Texas refineries unless sufficient objections are raised.

The scientific community needs to get involved in this fray now. If this project gains approval, it will become exceedingly difficult to control the tar sands monster.

Although there are multiple objections to tar sands development and the pipeline, including destruction of the environment in Canada¹ and the likelihood of spills along the pipeline's pathway, such objections, by themselves, are very unlikely to stop the project.

An overwhelming objection is that exploitation of tar sands would make it implausible to stabilize climate and avoid disastrous global climate impacts. The tar sands are estimated (e.g., see IPCC AR4 WG3 report) to contain at least 400 GtC (equivalent to about 200 ppm CO2).

Easily available reserves of conventional oil and gas are enough to take atmospheric CO2 well above 400 ppm. However, if emissions from coal are phased out over the next few decades and if unconventional fossil fuels are left in the ground, it is conceivable to stabilize climate ^2,3.

Phase out of emissions from coal is itself an enormous challenge. However, if the tar sands are thrown into the mix it is essentially game over. There is no practical way to capture the CO2 emitted while burning oil, which is used principally in vehicles. Continued...

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NASA Satellite Video of Tornadoes from Space

5 Days of Tornado-Generating Storms in U.S. Midwest [HD Video]

The U.S. Midwest was hammered by severe storms for the last several days and this animation of satellite imagery from the GOES-13 satellite shows the progression of storms from May 20 to 25, 2011. This animation includes the storms that spawned the deadly Joplin, Missouri tornado on May 22 (around 5:30 p.m.) and the Oklahoma tornado event (Oklahoma City and Piedmont, Oklahoma) on May 24, 2011.

The video shows the progression of the May 24 storms moving from Arkansas, Illinois and Missouri into Mississippi, Ohio, Kentucky, Tennessee and Indiana. The May 24 event killed people in Kansas, Arkansas and Oklahoma, according to the Associated Press. The National Weather Service reported that several twisters touched down in Oklahoma City and some of its suburbs.

The Geostationary Operational Environmental Satellite called GOES-13 covers weather events over the eastern U.S. and the Atlantic Ocean. The GOES series of satellites is operated by NOAA, and the NASA GOES Project creates images and animations from the GOES series of satellites. This movie is in a large-format 720x1280 H264-encoded digital movie from the GOES-13 satellite.

Movie Credit: NASA/NOAA GOES Project, Dennis Chesters
Caption: NASA/Rob Gutro

Credit: NOAA/NASA GOES Project

NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.

The Case for Young People and Nature: A Path to a Healthy, Natural, Prosperous Future

The Case for Young People and Nature: A Path to a Healthy, Natural, Prosperous Future describes what governments need to do to stabilize climate, fulfilling their obligation to young people and future generations. This is the science basis attached to suits being filed this week and in the future in different states and countries.

- Dr. James Hansen, NASA Goddard Institute of Space Sciences, Columbia University Earth Institute, New York

by James Hansen, Pushker Kharecha, Makiko Sato, Paul Epstein, Paul J. Hearty, Ove HoeghGuldberg, Camille Parmesan, Stefan Rahmstorf, Johan Rockstrom, Eelco J.Rohling, Jeffrey Sachs, Peter Smith, Karina von Schuckmann, James C. Zachos

Abstract. We describe scenarios that define how rapidly fossil fuel emissions must be phased down to restore Earth's energy balance and stabilize global climate. A scenario that stabilizes climate and preserves nature is technically possible and it is essential for the future of humanity. Despite overwhelming evidence, governments and the fossil fuel industry continue to propose that all fossil fuels must be exploited before the world turns predominantly to clean energies. If governments fail to adopt policies that cause rapid phase-down of fossil fuel emissions, today's children, future generations, and nature will bear the consequences through no fault of their own. Governments must act immediately to significantly reduce fossil fuel emissions to protect our children's future and avoid loss of crucial ecosystem services, or else be complicit in this loss and its consequences. Continued...

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Earth's Energy Imbalance and Implications

James Hansen, Makiko Sato, Pushker Kharecha, Karina von Schuckmann

Improving observations of ocean temperature confirm that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. This energy imbalance provides fundamental verification of the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain constrain the net climate forcing and ocean mixing rates. 

The basic physics underlying this global warming, the greenhouse effect, is simple. An increase of gases such as CO2 makes the atmosphere more opaque at infrared wavelengths. This added opacity causes the planet's heat radiation to space to arise from higher, colder levels in the atmosphere, thus reducing emission of heat energy to space. The temporary imbalance between the energy absorbed from the sun and heat emission to space, causes the planet to warm until planetary energy balance is restored. Continued...

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Perceptions of Climate Change

by James Hansen and Makiko Sato

This past winter, for the second year in a row, seemed pretty extreme in both Europe and the United States. So this is a good time to check quantitatively how seasonal climate change is stacking up against expectations.

People's perception of climate change may be the most important factor determining their willingness to accept the scientific conclusion that humans are causing global warming (or global climate disruption, as you please). It is hard to persuade people that they have lying eyes.

In the paper attached to my congressional testimony in 1988 (1) we asserted that the perceptive person would notice that climate was changing by the early 21st century. I used colored dice to illustrate how the frequency of unusually warm seasons was expected to change.

We considered three scenarios for future greenhouse gas amounts. Figure 1 shows that the real world so far is close to scenario B. Temporary aside: there are two main reasons that greenhouse gas growth moved off the track of scenario A onto scenario B in the early 1990s, as shown in Figure 2: (1) the growth of CFCs (chlorofluorocarbons) was greatly diminished by successive tightenings of the Montreal Protocol, (2) the growth of methane slowed sharply.

Fig. 1. Update of Fig. 2 of Reference 1, scenarios A, B and C being climate forcings of greenhouse gases used in climate model simulations. The real world (red curve) has closely followed scenario B.

Fig. 3. Surface temperature anomalies in Northern Hemisphere winter 2010-2011 relative to 1951-1980 mean. See reference 3.

Let's start with this past winter, compare it with the last few winters, and then check whether the odds of warm seasons have changed as expected.   Continued...

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Paleoclimate Implications for Human-Made Climate Change

by James E. Hansen and Makiko Sato

Climate change is likely to be the predominant scientific, economic, political and moral issue of the 21st century. The fate of humanity and nature may depend upon early recognition and understanding of human-made effects on Earth's climate (Hansen, 2009).

Tools for assessing the expected climate effects of alternative levels of human-made changes of atmospheric composition include (1) Earth's paleoclimate history, showing how climate responded in the past to changes of boundary conditions including atmospheric composition, (2) modern observations of climate change, especially global satellite observations, coincident with rapidly changing human-made and natural climate forcings, and (3) climate models and theory, which aid interpretation of observations on all time scales and are useful for projecting future climate under alternative climate forcing scenarios. Continued...

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Global Temperature and Europe's Frigid Air

by James Hansen, Reto Ruedy, Makiko Sato and Ken Lo

The cold anomaly in Northern Europe in November has continued and strengthened in the first half of December. Combined with the unusual cold winter of 2009-2010 in Northern Hemisphere mid-latitudes, this regional cold spell has caused widespread commentary that global warming has ended. That is hardly the case. On the contrary, globally November 2010 is the warmest November in the GISS record.

Link to the scientific paper →

Coal River Mountain Redux

Dr. James Hansen

Below is an update to the Coal River Mountain story that I described earlier in an e-mail, in an op-ed, and in "Storms of My Grandchildren".

Mike Roselle, of Climate Ground Zero in West Virginia, has an op-ed regarding his upcoming trial in Raleigh County, West Virginia. He was arrested for trespass while protesting blasting near the Brushy Fork impoundment of 8 billion gallons of toxic coal sludge located directly above Marsh Fork Elementary School. (No word yet on trial date for Larry Gibson, Daryl Hannah and me regarding our arrest on 23 June 2009 for "obstruction", when I was reading a request that Massey Energy provide funds for a new elementary school at a safe distance).

I got drawn into this by students at Virginia Tech, who fed me all the details when I gave a talk on their campus a couple of years ago. Underground Appalachian coal mining is being replaced in recent years by mountaintop removal. Big companies come in, dynamite the tops of the mountains, push the debris into the valleys, gather the coal from seams that are only several feet thick, and throw grass seed on what remains.

The number of jobs with this coal mining practice is small, and it leaves the environment in a shambles, the streams and underground water heavily polluted. But it pays off big for the few guys at the top. The head of Massey Energy, Don Blankenship, was paid $17.8 million in 2009 plus $27.2 million in deferred compensation. They must also have a lot of political clout, as it is hard to see how this abominable practice could continue otherwise. Continued...

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How Warm Was This Summer?

Dr. James Hansen

Let's look at the surface temperatures in the summer of 2010, which justifiably received a lot of attention. Figure 1 shows maps of the June-July-August temperature anomaly (relative to 1951-1980) in the GISS temperature analysis (described in paper in press at Rev. Geophys., available at this link) for 2009 and 2010, as well as maps for December-January-February (Northern Hemisphere winter, Southern Hemisphere summer) for the past two years.

June-July-August 2010 was the 4th warmest in the 131 year GISS analysis, while 2009 was the 2nd warmest¹.  2010 was a bit cooler than 2009 mainly because a moderate El Nino in the equatorial Pacific Ocean during late 2009 and early 2010 has been replaced by a moderate La Nina. Also most of Antarctica was cool in winter 2010, while it was warm in 2009. Antarctic winter temperature anomalies are very noisy, fluctuating chaotically from year to year.

The maps make clear that perceptions of how hot it was depend on where you live. The two warmest anomalies on the planet this past summer were Eastern Europe and the Antarctic Peninsula. Not many people live on the Antarctic Peninsula and an anomaly of even several degrees in winter there is not a big deal. But the warm anomaly centered in Eastern Europe, which covered most of Europe and the Middle East, was noticed, to say the least. It was also quite warm in Japan, where the prior summer had been cooler than the 1951-1980 mean. The United States, which had been unusually cool in the summer of 2009, was warm this past summer, except the Pacific Northwest, which was cooler than the 1951-1980 climatology. Continued...

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Activist

by Dr. James Hansen

"How did you become an activist?" I was surprised by the question. I never considered myself an activist. I am a slow-paced taciturn scientist from the Midwest. Most of my relatives are pretty conservative. I can imagine attitudes at home toward "activists".

I was about to protest the characterization – but I had been arrested, more than once. And I had testified in defense of others who had broken the law. Sure, we only meant to draw attention to problems of continued fossil fuel addiction. But weren't there other ways to do that in a democracy? How had I been sucked into being an "activist?"

My grandchildren had a lot to do with it. It happened step-by-step. First, in 2004, I broke a 15-year self-imposed effort to stay out of the media. I gave a public lecture, backed by scientific papers, showing the need to slow greenhouse gas emissions – and I criticized the Bush administration for lack of appropriate policies. My grandchildren came into the talk only as props – holding 1-watt Christmas tree bulbs to help explain climate forcings.

Fourteen months later I gave another public talk – connecting the dots from global warming to policy implications to criticisms of the fossil fuel industry for promoting misinformation. This time my grandchildren provided rationalization for a talk likely to draw Administration ire: I explained that I did not want my children to look back and say "Opa understood what was happening, but he never made it clear."

What had become clear was that our planet is close to climate tipping points. Ice is melting in the Arctic, on Greenland and Antarctica, and on mountain glaciers worldwide. Many species are stressed by environmental destruction and climate change. Continuing fossil fuel emissions, if unabated, will cause sea level rise and species extinction accelerating out of humanity's control. Increasing atmospheric water vapor is already magnifying climate extremes, increasing overall precipitation, causing greater floods and stronger storms.  Continued...

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What Global Warming Looks Like...So Far

Dr. James Hansen

Contrary to a popular misconception, the rate of warming has not declined. Global temperature is rising as fast in the past decade as in the prior two decades, despite year-to-year fluctuations associated with the El Nino-La Nina cycle of tropical ocean temperature. Record high global 12-month running-mean temperature for the period with instrumental data was reached in 2010.

The July 2010 global map of surface temperature anomalies (Figure 1), relative to the average July in the 1951-1980 period of climatology, provides a useful picture of current climate.

Figure 1.

It was more than 5°C (about 10°F) warmer than climatology in the eastern European region including Moscow. There was an area in eastern Asia that was similarly unusually hot. The eastern part of the United States was unusually warm, although not to the degree of the hot spots in Eurasia. There were also substantial areas cooler than climatology, including a region in central Asia and the southern part of South America. The emerging La Nina is now moderately strong, as evidenced by the region cooler than climatology along the equator in the eastern and central Pacific Ocean.

The global average July 2010 temperature was 0.55°C warmer than climatology in the GISS analysis, which puts 2010 in practically a three way tie for third warmest July. July 1998 was the warmest in the GISS analysis, at 0.68°C.  Continued...

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Global Surface Temperature Change

James Hansen, R. Ruedy, M. Sato, and K. Lo

NASA Goddard Institute for Space Studies, New York, New York, USA

"Record high global temperature during the period with instrumental data was reached in 2010"

We update the Goddard Institute for Space Studies (GISS) analysis of global surface temperature change, compare alternative analyses, and address questions about perception and reality of global warming. Satellite-observed nightlights are used to identify measurement stations located in extreme darkness and adjust temperature trends of urban and peri-urban stations for non-climatic factors, verifying that urban effects on analyzed global change are small. Because the GISS analysis combines available sea surface temperature records with meteorological station measurements, we test alternative choices for the ocean data, showing that global temperature change is sensitive to estimated temperature change in polar regions where observations are limited. We suggest use of 12-month (and n×12) running mean temperature to fully remove the annual cycle and improve information content in temperature graphs. We conclude that global temperature continued to rise rapidly in the past decade, despite large year-to-year fluctuations associated with the El Nino-La Nina cycle of tropical ocean temperature. Record high global temperature during the period with instrumental data was reached in 2010.

Summary:

Human-made climate change has become an issue of surpassing importance to humanity, and global warming is the first order manifestation of increasing greenhouse gases that are predicted to drive climate change. Thus it is understandable that analyses of ongoing global temperature change are now subject to increasing scrutiny and criticisms that are different than would occur for a purely scientific problem.  Continued...

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People's Climate Stewardship Act

by Dr. James Hansen

It's time to take back Earth Day.

Some of our best friends have become the planet's worst enemies.

The climate and energy bills in Congress were designed by big banks and fat-cat environmental organizations that have lost touch with the people and nature. 

The bills all use smoke-and-mirrors: cap-and-trade, offsets, and give-aways.

The truth is this: as long as fossil fuels are the cheapest energy we will go to the ends of Earth the deepest ocean, the most pristine land for the last drop of oil and gas, and destroy mountains for the last shard of coal.

But that would guarantee climate disasters for young people and nature – we would destroy creation.

Fossil fuels are cheapest only because they do not pay their costs to society – for damage to human health, the environment and future generations.

So today, based on discussions with religious leaders, congressional staffers, economists, and concerned citizens, I am proposing a People's Climate Stewardship bill. Continued...

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