Sunday, March 13, 2011
Impact of Climate
No one knows how much warming is "safe". What we do know is that climate change is already harming people and ecosystems. Its reality can be seen in melting glaciers, disintegrating polar ice, thawing permafrost, dying coral reefs, rising sea levels, changing ecosystems and fatal heAnd it is not only scientists that are witnessing these changes. From Inuit in the far north to islanders near the equator - people are already struggling with the impacts of climate change.at waves.But all of this is only the beginning. We are already experiencing dangerous climate change…we need to act to avoid catastrophic climate change. While not all regional effects are yet known, here are some likely future effects if we allow current trends to continue:Greenland and Antarctic ice sheet melting. Unless checked, warming from emissions may trigger the irreversible meltdown of the Greenland ice sheet in the coming decades, which would add up to seven meters of sea-level rise, over some centuries; there is new evidence that the rate of ice discharge from parts of the Antarctic mean that it is also at risk of meltdown.
Temperature Records
Groups of scientists from several major institutions — NASA's Goddard Institute for Space Studies (GISS), NOAA's National Climatic Data Center (NCDC), the Japanese Meteorological Agency and the Met Office Hadley Centre in the United Kingdom — tally data collected by temperature monitoring stations spread around the world and make an announcement about whether the previous year was a comparatively warm or cool year.
Multiple institutions monitor global surface temperatures. Despite subtle differences in the ways the scientists perform their analyses, these four widely referenced records show remarkable agreement. (Image credit: NASA Earth Observatory/Robert Simmon)
There are large areas in the Arctic without weather stations. NASA GISS approaches the problem by filling in gaps with data from the nearest land stations. The Climatic Research Unit at the University of East Anglia, which works jointly with the Met Office Hadley Centre, leaves much of the region out of its global temperature analysis. (Image credit: NASA Earth Observatory/Robert Simmon)
In 2010, global temperatures continued to rise. A new analysis from the Goddard Institute for Space Studies shows that 2010 tied with 2005 as the warmest year on record, and was part of the warmest decade on record. The thin line represents annual data, while the thick line is a five-year running mean. (Image credit: NASA Earth Observatory/Robert Simmon)
NASA's announcement this year — that 2010 ties 2005 as the warmest year in the 131-year instrumental record — made headlines. But, how much does the ranking of a single year matter?
Not all that much, emphasizes James Hansen, the director of NASA's Goddard Institute for Space Studies (GISS) in New York City. In the GISS analysis, for example, 2010 differed from 2005 by less than 0.01°C (0.018°F), a difference so small that the temperatures of these two years are indistinguishable, given the uncertainty of the calculation.
Meanwhile, the third warmest year — 2009 — is so close to 1998, 2002, 2003, 2006, and 2007, with the maximum difference between the years being a mere 0.03°C, that all six years are virtually tied.
Even for a near record-breaking year like 2010 the broader context is more important than a single year. "Certainly, it is interesting that 2010 was so warm despite the presence of a La Niña and a remarkably inactive sun, two factors that have a cooling influence on the planet, but far more important than any particular year's ranking are the decadal trends," Hansen said.
One of the problems with focusing on annual rankings, rather than the longer trend, is that the rankings of individual years often differ in the most closely watched temperature analyses — from GISS, NCDC, and the Met Office — a situation that can generate confusion.
For example, while GISS previously ranked 2005 warmest, the Met Office listed 1998 warmest. The discrepancy helped fuel the misperception that findings from the three groups vary sharply or contain large amounts of uncertainty. It also fueled the misperception that global warming stopped in 1998.
"In reality, nothing could be further from the truth," said Hansen. Global temperatures have continued to rise steadily.
"The three official records vary slightly because of subtle differences in the way we analyze the data, but they agree extraordinarily well," said Reto Ruedy, one of Hansen's colleagues at GISS who helps analyze global surface temperatures.
All three records show peaks and valleys that vary in virtual sync with each other since 1880. All three show particularly rapid warming in the last few decades. And all three show the last decade is the warmest in the instrumental record.
Multiple institutions monitor global surface temperatures. Despite subtle differences in the ways the scientists perform their analyses, these four widely referenced records show remarkable agreement. (Image credit: NASA Earth Observatory/Robert Simmon)
There are large areas in the Arctic without weather stations. NASA GISS approaches the problem by filling in gaps with data from the nearest land stations. The Climatic Research Unit at the University of East Anglia, which works jointly with the Met Office Hadley Centre, leaves much of the region out of its global temperature analysis. (Image credit: NASA Earth Observatory/Robert Simmon)
In 2010, global temperatures continued to rise. A new analysis from the Goddard Institute for Space Studies shows that 2010 tied with 2005 as the warmest year on record, and was part of the warmest decade on record. The thin line represents annual data, while the thick line is a five-year running mean. (Image credit: NASA Earth Observatory/Robert Simmon)
NASA's announcement this year — that 2010 ties 2005 as the warmest year in the 131-year instrumental record — made headlines. But, how much does the ranking of a single year matter?
Not all that much, emphasizes James Hansen, the director of NASA's Goddard Institute for Space Studies (GISS) in New York City. In the GISS analysis, for example, 2010 differed from 2005 by less than 0.01°C (0.018°F), a difference so small that the temperatures of these two years are indistinguishable, given the uncertainty of the calculation.
Meanwhile, the third warmest year — 2009 — is so close to 1998, 2002, 2003, 2006, and 2007, with the maximum difference between the years being a mere 0.03°C, that all six years are virtually tied.
Even for a near record-breaking year like 2010 the broader context is more important than a single year. "Certainly, it is interesting that 2010 was so warm despite the presence of a La Niña and a remarkably inactive sun, two factors that have a cooling influence on the planet, but far more important than any particular year's ranking are the decadal trends," Hansen said.
One of the problems with focusing on annual rankings, rather than the longer trend, is that the rankings of individual years often differ in the most closely watched temperature analyses — from GISS, NCDC, and the Met Office — a situation that can generate confusion.
For example, while GISS previously ranked 2005 warmest, the Met Office listed 1998 warmest. The discrepancy helped fuel the misperception that findings from the three groups vary sharply or contain large amounts of uncertainty. It also fueled the misperception that global warming stopped in 1998.
"In reality, nothing could be further from the truth," said Hansen. Global temperatures have continued to rise steadily.
"The three official records vary slightly because of subtle differences in the way we analyze the data, but they agree extraordinarily well," said Reto Ruedy, one of Hansen's colleagues at GISS who helps analyze global surface temperatures.
All three records show peaks and valleys that vary in virtual sync with each other since 1880. All three show particularly rapid warming in the last few decades. And all three show the last decade is the warmest in the instrumental record.
Tuesday, March 1, 2011
Global Warming
Climate model projections summarized in the latest IPCC report indicate that the global surface temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century. The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts. Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers, permafrost and sea ice. Other likely effects include changes in the frequency and intensity of extreme weather events, species extinctions, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional variations is uncertain. As a result of contemporary increases in atmospheric carbon dioxide, the oceans have becomemore acidic, a result that is predicted to continue
Subscribe to:
Posts (Atom)