Scientific consensus: Earth's climate is warming

Scientific consensus: Earth's climate is warming:

 Most leading scientific organizations worldwide have issued public statements endorsing the position that climate-warming trends over the past century are extremely likely due to human activities.
Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems

Multiple studies published in peer-reviewed scientific journals1 show that 97 percent or more of actively publishing climate scientists agree: Climate-warming trends over the past century are extremely likely due to human activities. In addition, most of the leading scientific organizations worldwide have issued public statements endorsing this position. The following is a partial list of these organizations, along with links to their published statements and a selection of related resources.

Climate change is real. There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems.

 It is likely that most of the warming in recent decades can be attributed to human activities

Statement on climate change from 18 scientific associations

"Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver." (2009)2

American Association for the Advancement of Science
"The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society." (2006)3

American Chemical Society
"Comprehensive scientific assessments of our current and potential future climates clearly indicate that climate change is real, largely attributable to emissions from human activities, and potentially a very serious problem." (2004)4

American Geophysical Union
"Human‐induced climate change requires urgent action. Humanity is the major influence on the global climate change observed over the past 50 years. Rapid societal responses can significantly lessen negative outcomes." (Adopted 2003, revised and reaffirmed 2007, 2012, 2013)5

American Medical Association
"Our AMA ... supports the findings of the Intergovernmental Panel on Climate Change’s fourth assessment report and concurs with the scientific consensus that the Earth is undergoing adverse global climate change and that anthropogenic contributions are significant." (2013)6

American Meteorological Society
"It is clear from extensive scientific evidence that the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases, including carbon dioxide (CO2), chlorofluorocarbons, methane, and nitrous oxide." (2012)7

American Physical Society
"The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now." 

The Geological Society of America
"The Geological Society of America (GSA) concurs with assessments by the National Academies of Science (2005), the National Research Council (2006), and the Intergovernmental Panel on Climate Change (IPCC, 2007) that global climate has warmed and that human activities (mainly greenhouse‐gas emissions) account for most of the warming since the middle 1900s." (2006; revised 2010)9

U.S. National Academy of Sciences
"The scientific understanding of climate change is now sufficiently clear to justify taking steps to reduce the amount of greenhouse gases in the atmosphere." (2005)11

U.S. Global Change Research Program
"The global warming of the past 50 years is due primarily to human-induced increases in heat-trapping gases. Human 'fingerprints' also have been identified in many other aspects of the climate system, including changes in ocean heat content, precipitation, atmospheric moisture, and Arctic sea ice." (2009, 13 U.S. government departments and agencies)12

Intergovernmental Panel on Climate Change
“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.”13

The following page lists the nearly 200 worldwide scientific organizations that hold the position that climate change has been caused by human action.

U.S. agencies

The following page contains information on what federal agencies are doing to adapt to climate change.

NOAA: March 2016 Was the Most Abnormally Warm Month on Record.

Data released on Thursday shows that March 2016 was the warmest March since at least 1891, making it the planet's 11th consecutive month to set a global temperature milestone. Scientists are witnessing the effects of climate change. The global average surface temperature in March was 0.62 degrees Celsius, or 1.16 degrees Fahrenheit, above the 1981-2010 average. When measured against the 20th century average, the month looks even more unusual, at 1.07 degrees Celsius, or 1.9 degrees Fahrenheit, above average. March 2016 follows the most two most unusually warm months on record, which occurred in January and February. 

NOAA reports that March 2016 Was the Most Abnormally Warm Month on Record For the Planet, ever.

Alaska, Canada, Greenland, Central Siberia, and the Urals all experienced the most abnormally warm March, with temperatures 4 to 6 degrees Celsius above the average. In the Arctic, Greenland commenced its melt season more than one month early with temperatures skyrocketing into 60 degrees Fahrenheit in southwest Greenland and breaking records all the way to the top of the ice sheet itself, more than 10,000 feet above sea level. 

Earth's global temperatures in March 2016 were the most abnormally warm on record for any month, according to NOAA. This is the second month in a row that this remarkable feat has occurred. March 2016 is also the eleventh consecutive month in a row that the earth has recorded its warmest respective month on record. In addition to NOAA, three other agencies confirmed that this past March was the warmest on record. The Japan Meteorological Agency (JMA) calculated the global mean March 2016 temperature was 0.62 degrees Celsius (about 1.1 degrees Fahrenheit) above the March 30-year average from 1981-2010. A second analysis from NASA's Goddard Institute for Space Studies also concluded March anomalies were the highest in their period of record dating to 1880, a whopping 1.28 degrees Celsius above the 1951-1980 average period. NASA found the March 2016 anomaly crushed the previous March record by over 0.3 degrees. NOAA's global State of the Climate report released Tuesday found March's temperature over the Earth's surface was 1.22 degrees Celsius above the 20th century average, not only crushing the warmest March in the 137-year period of record set just one year prior, but also the largest temperature anomaly of any month in NOAA's database dating to 1880.

Whether one looks at a 12-month running average, 5-year average, or 30-year trends, all show stark increases in global average surface temperatures, which scientists have concluded is largely attributable to human-caused greenhouse gas emissions from the burning of fossil fuels.

Greenland is experiencing a early spring thaw.

The 2012 melt season, according to the National Snow and Ice Data Center, experienced melting even at mountainous heights over a mile into the sky atop Greenland. “During a peak melt event in July, even the summit areas of the ice sheet, nearly two miles above sea level, saw snowmelt conditions,” the group wrote. “While this has been observed in ice cores a handful of times in the past 1,000 years, it had not previously occurred in this century.” That’s not normal. 

A vast region of Greenland is experiencing a freakishly early spring thaw. Summer-like temperatures—a balmy 10 degrees Celsius (50 degrees Fahrenheit)—have created a melt area encompassing 12 percent of the planet’s northernmost ice sheet, according to analysis by the Danish Meteorological Institute (DMI). 
Almost 12% of Greenland’s ice sheet was melting on Monday, according to data crunched by the Danish Meteorological Institute. It beat by almost a month the previous record for a melt of more than 10%, on 5 May 2010.

“We had to check that our models were still working properly,”6 Peter Langen, climate scientist at DMI, told blog Polar Portal. Temperature readings on the ice were in line with the numbers, however, exceeding 10C in some places. Even a weather station 1840 metres above sea level recorded a maximum of 3.1C, which data analysts said would be warm for July, let alone April. Greenland’s usual melt season runs from early June to September. “Too much. Too early,” tweeted the World Meteorological Organisation.

Widespread melting on the Greenland ice sheet typically doesn’t get going until May. In fact, the three earliest dates for a melt area exceeding 10 percent are May 5, 2010, May 8, 1990, and May 8, 2006. “It is a very unusual situation, especially so early in the year,” climate scientist Martin Stendel said in a blog post, adding that cold air and low pressure systems to the east and west of Greenland have forced a warm air “cap” over the island.

Researchers attributed the surprising early melt this year to weather conditions, and more specifically, a warm midlatitude air mass getting stuck over the ice sheet. “The strong south air flow onto Greenland has produced warm air, rain instead of snow, and melting of snow that is in Nuuk,” Greenland’s capital, Jason Box, a researcher with the Geological Survey of Denmark and Greenland, said by email. So, what’ll happen to all that meltwater swimming atop of the ice sheet this week? In all likelihood, temperatures will soon drop, and it’ll percolate into the snow and refreeze, meteorologist Ruth Mottram of the DMI told New Scientist. But by doing so, the meltwater will carry heat energy to lower depths, reducing the amount required to thaw the ice out later. And if past years are any indicator, Greenland is in for another hot, melty summer.

In other words, time to bust out your rain boots if you live in Miami.

Contribution of Antarctica to past and future sea-level rise.

Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sea level has been 6–9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability.

 Here we use a model coupling ice sheet and climate dynamics—including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs—that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.

If we use numerical climate simulations, paleoclimate data, and modern observations to study the effect of growing ice melt from Antarctica and Greenland. 

 We hypothesize that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response. Doubling times of 10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200 years. Recent ice melt doubling times are near the lower end of the 10–40-year range, but the record is too short to confirm the nature of the response. 

The feedbacks, including subsurface ocean warming, help explain paleoclimate data and point to a dominant Southern Ocean role in controlling atmospheric CO2, which in turn exercised tight control on global temperature and sea level. The millennial (500–2000-year) timescale of deep-ocean ventilation affects the timescale for natural CO2 change and thus the timescale for paleo-global climate, ice sheet, and sea level changes, but this paleo-millennial timescale should not be misinterpreted as the timescale for ice sheet response to a rapid, large, human-made climate forcing. These climate feedbacks aid interpretation of events late in the prior interglacial, when sea level rose to +6–9 m with evidence of extreme storms while Earth was less than 1 °C warmer than today. Ice melt cooling of the North Atlantic and Southern oceans increases atmospheric temperature gradients, eddy kinetic energy and baroclinicity, thus driving more powerful storms. The modeling, paleoclimate evidence, and ongoing observations together imply that 2 °C global warming above the preindustrial level could be dangerous. Continued high fossil fuel emissions this century are predicted to yield (1) cooling of the Southern Ocean, especially in the Western Hemisphere; (2) slowing of the Southern Ocean overturning circulation, warming of the ice shelves, and growing ice sheet mass loss; (3) slowdown and eventual shutdown of the Atlantic overturning circulation with cooling of the North Atlantic region; (4) increasingly powerful storms; and (5) nonlinearly growing sea level rise, reaching several meters over a timescale of 50–150 years. These predictions, especially the cooling in the Southern Ocean and North Atlantic with markedly reduced warming or even cooling in Europe, differ fundamentally from existing climate change assessments. We discuss observations and modeling studies needed to refute or clarify these assertions.

Meltwater tends to stabilize the ocean column, inducing amplifying feedbacks that increase subsurface ocean warming and ice shelf melting. Cold meltwater and induced dynamical effects cause ocean surface cooling in the Southern Ocean and North Atlantic, thus increasing Earth's energy imbalance and heat flux into most of the global ocean's surface. Southern Ocean surface cooling, while lower latitudes are warming, increases precipitation on the Southern Ocean, increasing ocean stratification, slowing deepwater formation, and increasing ice sheet mass loss. These feedbacks make ice sheets in contact with the ocean vulnerable to accelerating disintegration

What is happening in the Arctic now is unprecedented & possibly catastrophic.

"What is happening in the Arctic now is unprecedented & possibly catastrophic."

That is from a world-known scientist, Dr. Peter Gleick, who is a member of the US National Academy of Science, a MacArthur Fellow, and President of the Pacific Institute. 

This is not a "national crisis". This is a threat to life on this planet as we know it. I won't stop talking about it until we, and our leaders, start to realize how severe it is.

Do you think climate silence is a conspiracy by a few major media corporations - or is it possible that all of us are so addicted to fossil fuels, we really don't want to know? To be honest, I can barely bring myself to read the latest news. Maybe the problems in the Arctic are just too big to comprehend, or just too scary to face? Is it worthwhile to keep fighting, if all we can do is slow down the loss - and the damage, for the next generation? There is, says Gleick, a big difference between a civilization facing severe challenges as the Earth warms, and a planet where climate changes so far and so fast that civilization cannot cope or adapt. We'll have to make major efforts to adapt to what we have already done. We can't continue to make it worse.

Let's say Greenland ice loss doubles or triples, and the Arctic sea ice disappears for most of the year. Gleick agrees nobody knows what would happen. When we change the greenhouse gases in the atmosphere, we are running a giant experiment on the Earth. It's already out of control.

January Arctic sea ice extent was the lowest in the satellite record, attended by unusually high air temperatures over the Arctic Ocean. January 2016 was a remarkably warm month. Air temperatures were more than 6 degrees Celsius (13 degrees Fahrenheit) above average across most of the Arctic Ocean. The Arctic is absorbing a lot more solar energy, and at a much greater rate, than anywhere else on the planet. In the last number of decades, the Arctic temperature has risen 1.0C per decade whereas the global average temperature rise has been about 0.15C per decade. Arctic sea ice extent for February averaged 14.22 million square kilometers (5.48 million square miles), the lowest February extent in the satellite record. It is 1.16 million square kilometers (448,000 square miles) below the 1981 to 2010 long-term average of 15.4 million square kilometers (5.94 million square miles) and is 200,000 square kilometers (77,000 square miles) below the previous record low for the month recorded in 2005.

The first three weeks of February saw little ice growth, but extent rose during the last week of the month primarily due to growth in the Sea of Okhotsk (180,000 square kilometers or 70,000 square miles) and to a lesser extent in Baffin Bay (35,000 square kilometers or 13,500 square miles). Extent is presently below average in the Barents and Kara seas, as well as the Bering Sea and the East Greenland Sea. Extent decreased in the Barents and East Greenland seas during the month of February. In other regions, such as the Sea of Okhotsk, Baffin Bay, and the Labrador Sea, ice conditions are near average to slightly above average for this time of year. An exception is the Gulf of St. Lawrence, which remains largely ice free.

Cryosphere climate change is not like air or water pollution, where the impacts remain local and when addressed, allow ecosystems largely to recover. Cryosphere climate change, driven by the physical laws of water’s response to the freezing point, is different. Slow to manifest itself, once triggered it inevitably forces the Earth’s climate system into a new state, one that most scientists believe has not existed for 35–50 million years. Adaptation to the levels of projected climate-related disruption, particularly sea-level rise that cannot be halted and accelerates over the centuries, simply will not be possible without massive migration and other changes to human centers of population and infrastructure, that will carry enormous economic and not least, historic and cultural costs. The only way fully to avoid these risks is never to let temperatures rise into these risk zones. After the climate is broken, and the cryosphere starts it's unstoppable melt, there is no way to "fix" it. Basically: humans will have to leave their coastal cities behind, and the some of the most fertile near-ocean river estuaries that now support many millions of people.

Here is what the ICCI says in a summary about this report:

"Policy makers and the general public alike now largely accept that the Arctic, Antarctica and many mountain regions already have warmed two-three times faster than the rest of the planet. What is less understood, outside the scientific community, is that the very nature of the cryosphere – regions of snow and ice – carries dynamics that once triggered, in some cases cannot be reversed, even with a return to lower temperatures or CO2 levels."

Humans are emitting about 10 billion tons of CO2 annually, changing the planet much more rapidly than at any time in the last 66 million years, according to a new study. “The anthropogenic release outpaces carbon release during the most extreme global warming event of the past 66 million years, by at least an order of magnitude,” writes Peter Stassen, an Earth and environmental scientist at KU Leuven, in Belgium." “If you look over the entire Cenozoic, the last 66 million years, the only event that we know of at the moment, that has a massive carbon release, and happens over a relatively short period of time, is the PETM,” says Zeebe. “We actually have to go back to relatively old periods, because in the more recent past, we don’t see anything comparable to what humans are currently doing.”

“The scary conclusion is that the East Siberian Arctic Shelf (ESAS) alone holds up to 1700 Gt of methane in the form of methane hydrates and free gas in shallow water, of which 50 Gt is ready for release at any time. The warning signs keep getting stronger,” For comparison purposes, there is currently 5 Gt of methane in the atmosphere. An abrupt release of 50 Gt would be very, very, bad! This is the nightmare scenario that keep scientists up at night.

This is not a "national" crisis. This is a threat to all humanity.

This is not a "national" crisis. This is a threat to all humanity.

Atmospheric CO2 is now reaching levels comparable to those seen during the Middle Miocene. A period of time when the world was both much warmer than today and sea levels were far, far higher. Each year that greenhouse gas emissions continue, more heat, more sea level rise, and more future dangerous climate change is locked in. (Image source: The Keeling Curve.)

“I have talked to scientists all over the world. And what they are telling me — if we don’t get our act together — this planet could be 5-10 degrees warmer by the end of this Century! Cataclysmic problems for this planet! This is a national crisis!” — Bernie Sanders, Michigan Democratic Debate, March 6th.

Sorry, Senator Sanders. It's much, much worse than that.
 2 degrees C warming by 2100, even if we were to make the monumental strides necessary to achieve that limit, is by itself pretty terrible. Though nowhere near as catastrophic as the 3, 4, 5 or 6 C levels of heating that are entirely possible if the world keeps going all out to extract and burn coal, oil and gas, it’s a rate of temperature increase not seen in 55 million years and a level of warming not seen in 2-3 million years. It locks in severe heatwaves the likes of which we’ve never seen before, terrible wildfires, extraordinary rainfall and droughts, monster storms, city-wrecking sea level rise, habitat loss, ocean health decline, glacial melt on a scale that changes the very complexion of the Earth, sea ice winnowing away to a shadow of its former coverage, amplifying Earth System feedbacks, and a whole host of other problems. It also means that the Earth continues to heat up for hundreds of years more unless greenhouse gasses are somehow drawn down — resulting in a long term warming in the range of 4 C so long as climate sensitivity is about what we’ve come to expect from our study of paleoclimate.


Climate Change: The state of the Science

Published on Nov 19, 2013
Produced by the International Geosphere-Biosphere Programme and Globaia and funded by the UN Foundation.

The data visualization summarises and visualizes several of the most significant statements in the Intergovernmental Panel on Climate Change's (IPCC) recent Fifth Assessment Report, (Working Group I summary for policymakers, the Physical Science Basis). In 2014, IPCC will publish summaries concerning societal impacts, mitigation and adaptation.

The statements and facts presented are derived from the IPCC summary for policymakers.

Our planet is vast. It is difficult to comprehend the scale. It is difficult too to comprehend the scale of humanity and the vast changes we've wrought in a lifetime. Population, production and consumption have grown exponentially. Roads, railways, airlines, shipping routes. The digital revolution. We've created a globally interconnected society. Evidence is mounting we've entered the Anthropocene.

Humanity is altering Earth's life support system. Carbon dioxide emissions are accelerating. Greenhouse gas levels are unprecedented in human history. The climate system is changing rapidly. The Intergovernmental Panel on Climate Change assesses the risks and options for societies. Its latest report states it is extremely likely humans are the dominant cause of warming in the past 60 years. Without deep emissions cuts, it is likely Earth will cross the target of two degree Celsius above pre-industrial levels. The target set by international policy. This could happen as early as 2050. If emissions keep rising at current rates, a four-degree rise by 2100 is as likely as not. This marks a vast transformation of our planet.

It is very likely heatwaves will occur more often and last longer. The Arctic will warm faster than the global average. It is likely sea ice will all but vanish in summer within decades if high emissions continue. It is very likely sea-level rise will accelerate. Cities and coastal areas are vulnerable. In general, wet regions are set to get wetter, dry regions drier. Monsoons are likely to become longer, their footprint likely to grow and downpours likely to intensify. The acidity of the ocean has increased 26% since the start of the industrial revolution. The full consequences of all these changes on the Earth system are unknown.

Humanity's carbon footprint is huge. Societies will need to adapt to climate change. The scale of change depends on decisions made now. Can we remain below two degrees? It is possible. But it is up to societies now to decide the future we want. For a likely chance of achieving the two-degree target, societies can emit another 250 billion tonnes of carbon. We burn about 10 billion tonnes of carbon a year. At current rates we will use this budget in about 25 years.
Download the IPCC Working Group I summary for policymakers (The Physical Science Basis) here:

Produced and directed by
Owen Gaffney and Félix Pharand-Deschênes

Félix Pharand-Deschênes

Owen Gaffney
International Geosphere-Biosphere Programme

Sarah Sherborne

GEOS-5 atmospheric model
NASA/Goddard Space Flight Center Scientific Visualization Studio
Suomi NPP VIIRS Nighttime Lights 2012
Earth Observation Group, NOAA National Geophysical Data Center
Landscan 2011tm High Resolution global Population Data Set
UT-Battelle, LLC, Oak Ridge National Laboratory
Blue Marble: Next Generation, Reto Stöckli
NASA Earth Observatory, NASA Goddard Space Flight Center
Annual temperature anomaly compared to 1860-1899 period
GFDL-CM3 (historical and RCP8.5 experiments) 1860-2100
Coupled Model Intercomparison Project Phase 5 (CMIP5)
September sea ice concentration
GFDL-CM3 (historical and RCP8.5 experiments) 1860-2100
Coupled Model Intercomparison Project Phase 5 (CMIP5)
Sea level rise flooded areas
Centers for the Remote Sensing of Ice Sheets (CReSIS)
Cyclones tracks
International Best Track Archive for Climate Stewardship (IBTrACS)
Ocean acidification
Max Planck Institute Earth System Model, RCP 8.5

Continuo VII • Microcosmos • Mind over Matter

Commissioned by
International Geosphere-Biosphere Programme
For the launch of the Intergovernmental Panel on Climate Change Working Group I summary for policymakers (Fifth Assessment Report)

Funded by
United Nations Foundation

Anne-Marie Doucet, Louve & Isis, Myles Allen, Catherine Boire, Wendy Broadgate, David Huard, Tatiana Ilyina, Kalee Kreider, Naomi Lubick, Jochem Marotzke, Johannes Mengel, Tim Nuthall, Sybil Seitzinger, Sturle Hauge Simonsen, Karen Smyth, Simon Torok, Denise Young

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