Jan. 2, 2013 — The new study, published January 2 in the journal Nature, examined the probability of keeping average global temperatures from rising more than 2°C above preindustrial levels under varying levels of climate policy stringency, and thus mitigation costs. In addition, the study for the first time quantified and ranked the uncertainties associated with efforts to mitigate climate change, including questions about the climate itself, uncertainties related to future technologies and energy demand, and political uncertainties as to when action will be taken.

The most important uncertainty, according to the study, is political -- that is, the question of when countries will begin to take serious action to reduce greenhouse gas emissions and implement other policies that could help mitigate climate change. Keywan Riahi, IIASA energy program leader and study co-author says, "With a twenty-year delay, you can throw as much money as you have at the problem, and the best outcome you can get is a fifty-fifty chance of keeping temperature rise below two degrees." Two degrees is the level that is currently supported by over 190 countries as a limit to avoid dangerous climate change.

Social uncertainties, which influence consumer energy demand, were second-most important, the study found. Social uncertainties refer to things like people's awareness and choices with respect to energy and to the adoption of efficient technologies.

"How much energy the world consumes going forward turns out to be a much bigger swing factor for climate change than the availability of technologies like solar and wind power, biofuels, and so on," said IIASA researcher David McCollum, another co-author. "Energy efficiency, improved urban planning, lifestyle changes -- these things on the demand side of the energy equation are so important; yet they receive relatively little attention compared to the supply side."

Climate change is a defining issue for our time. The geological record contains abundant evidence of the ways in which Earth’s climate has changed in the past. That evidence is highly relevant to understanding how it may change in the future. The Council of the Society is issuing this statement as part of the Society’s work “to promote all forms of education, awareness and understanding of the Earth and their practical applications for the benefit of the public globally”. The statement is intended for non-specialists and Fellows of the Society. It is based on analysis of geological evidence, and not on analysis of recent temperature or satellite data, or climate model projections. It contains references to support key statements, indicated by superscript numbers, and a reading list for those who wish to explore the subject further.

What is climate change, and how do geologists know about it?
The Earth’s temperature and weather patterns change naturally over time scales ranging from decades, to hundreds of thousands, to millions of years1. The climate is the statistical average of the weather taken over a long period, typically 30 years. It is never static, but subject to constant disturbances, sometimes minor in nature and effect, but at other times much larger. In some cases these changes are gradual and in others abrupt.

Evidence for climate change is preserved in a wide range of geological settings, including marine and lake sediments, ice sheets, fossil corals, stalagmites and fossil tree rings. Advances in field observation, laboratory techniques and numerical modelling allow geoscientists to show, with increasing confidence, how and why climate has changed in the past. For example, cores drilled through the ice sheets yield a record of polar temperatures and atmospheric composition ranging back to 120,000 years in Greenland and 800,000 years in Antarctica. Oceanic sediments preserve a record reaching back tens of millions of years, and older sedimentary rocks extend the record to hundreds of millions of years. This vital baseline of knowledge about the past provides the context for estimating likely changes in the future.

What are the grounds for concern?
The last century has seen a rapidly growing global population and much more intensive use of resources, leading to greatly increased emissions of gases, such as carbon dioxide and methane, from the burning of fossil fuels (oil, gas and coal), and from agriculture, cement production and deforestation. Evidence from the geological record is consistent with the physics that shows that adding large amounts of carbon dioxide to the atmosphere warms the world and may lead to: higher sea levels and flooding of low-lying coasts; greatly changed patterns of rainfall2; increased acidity of the oceans 3,4,5,6; and decreased oxygen levels in seawater7,8,9.

Natural Relationship Between Carbon Dioxide Concentrations and Sea Level Documented

Jan. 2, 2013 — By comparing reconstructions of atmospheric carbon dioxide (CO2) concentrations and sea level over the past 40 million years, researchers based at the National Oceanography Centre, Southampton have found that greenhouse gas concentrations similar to the present (almost 400 parts per million) were systematically associated with sea levels at least nine metres above current levels.

"With a twenty-year delay, you can throw as much money as you have at the problem, and the best outcome you can get is a fifty-fifty chance of keeping temperature rise below two degrees.

Is It Happening?

Yes. Earth is already showing many signs of worldwide climate change.

• Average temperatures have climbed 1.4 degrees Fahrenheit (0.8 degree Celsius) around the world since 1880, much of this in recent decades, according to NASA's Goddard Institute for Space Studies.

• The rate of warming is increasing. The 20th century's last two decades were the hottest in 400 years and possibly the warmest for several millennia, according to a number of climate studies. And the United Nations' Intergovernmental Panel on Climate Change (IPCC) reports that 11 of the past 12 years are among the dozen warmest since 1850.

• The Arctic is feeling the effects the most. Average temperatures in Alaska, western Canada, and eastern Russia have risen at twice the global average, according to the multinational Arctic Climate Impact Assessment report compiled between 2000 and 2004.

• Arctic ice is rapidly disappearing, and the region may have its first completely ice-free summer by 2040 or earlier. Polar bears and indigenous cultures are already suffering from the sea-ice loss.

• Glaciers and mountain snows are rapidly melting—for example, Montana's Glacier National Park now has only 27 glaciers, versus 150 in 1910. In the Northern Hemisphere, thaws also come a week earlier in spring and freezes begin a week later.

• Coral reefs, which are highly sensitive to small changes in water temperature, suffered the worst bleaching—or die-off in response to stress—ever recorded in 1998, with some areas seeing bleach rates of 70 percent. Experts expect these sorts of events to increase in frequency and intensity in the next 50 years as sea temperatures rise.

• An upsurge in the amount of extreme weather events, such as wildfires, heat waves, and strong tropical storms, is also attributed in part to climate change by some experts.

Are Humans Causing it?

The report, based on the work of some 2,500 scientists in more than 130 countries, concluded that humans have caused all or most of the current planetary warming. Human-caused global warming is often called anthropogenic climate change.
• Industrialization, deforestation, and pollution have greatly increased atmospheric concentrations of water vapor, carbon dioxide, methane, and nitrous oxide, all greenhouse gases that help trap heat near Earth's surface. (See an interactive feature on how global warming works.)

• Humans are pouring carbon dioxide into the atmosphere much faster than plants and oceans can absorb it.

• These gases persist in the atmosphere for years, meaning that even if such emissions were eliminated today, it would not immediately stop global warming.

• Some experts point out that natural cycles in Earth's orbit can alter the planet's exposure to sunlight, which may explain the current trend. Earth has indeed experienced warming and cooling cycles roughly every hundred thousand years due to these orbital shifts, but such changes have occurred over the span of several centuries. Today's changes have taken place over the past hundred years or less.

• Other recent research has suggested that the effects of variations in the sun's output are "negligible" as a factor in warming, but other, more complicated solar mechanisms could possibly play a role.

True. I'll move it.

psketti wrote: Can you tell me of a single issue that is more relevant to today's world?

Maybe you don't really understand how bad AGW could be?

What do you do about all those things you mentioned there andyh?

psketti wrote: Can you tell me of a single issue that is more relevant to today's world?

Maybe you don't really understand how bad AGW could be?

What do you do about all those things you mentioned there andyh?

I think this whole thing could be solved fairly quickly and fairly conclusively, if money/growth wasn't the sole determining factor in the reasoning of those in the position to do something about it.

The same things that solve global warming, would have a huge effect on the problems of the Global Capitalist system andyh highlights.

Na P, it's ok.