Climate Penguin
The extent of summer sea ice covering the Arctic Ocean is now decreasing by a rate of about 13 percent per decade, compared to the 1979-2000 average. The six lowest annual minimum extents on record have been in the last six years; in 2012, Arctic sea ice extent reached its lowest level in the satellite record, fully 760,000 square kilometers (293,000 square miles) below the previous record, which occurred in 2007. That difference is an area about the size of the state of Texas. The 2012 minimum was in turn 3.29 million square kilometers (1.27 million square miles) (or 49 percent) below the 1979 to 2000 average minimum, representing an area nearly twice the size of the state of Alaska.
4. Arctic Sea Ice Is in a 'Death Spiral'
3. The Rate of Warming Is Unprecedented in at Least 11,000 Years
5. Greenland Is Losing Ice at an Accelerating Rate
6. Antarctic Peninsula Is Also Losing Ice at an Accelerating Rate
Much of Antarctica is warming, but the Antarctic Peninsula - the region that reaches northward toward the tip of South America - is actually the most rapidly-warming part of the Southern Hemisphere, having seen temperatures increase by about 2.8 degrees Celsius over the last 50 years. Even when ice shelves don't collapse, their surfaces partially melt during summer - and according to new research, they are doing so now at a rate more than ten times greater than 600 years ago. According to one of the study's authors, "the melting we observe at this site in the past few decades has no similar analogue in the past 1000 years - here we can say the level of melting observed today is unique in the context of the past 1000 years."
7. The Ocean Is Warming
Inevitably, much of the climate attention focuses on the planet's surface - because that's the part where we live. But 90 percent of global warming goes into heating, not the land or atmosphere, but the ocean. Because it takes far more energy to heat up the entire ocean than the lower atmosphere or a surface layer of ice, the amount that the ocean has warmed is much less than on land: on average, about 0.025 degrees Celsius a decade - or slightly more than one-tenth of a degree Celsius over the last 50 years. Interestingly, this warming is not just affecting the surface of the sea; 30 percent of ocean warming has been taking place in waters deeper than 700 meters, and some has even occurred in the deepest, abyssal waters of the ocean. This deep-water warming is most pronounced in the Southern Ocean around Antarctica, which is warming at roughly 0.03 degrees Celsius a decade, although most abyssal oceans are warming at around one-tenth that rate.
8. Sea Level Is Rising
Despite skeptic assertions to the contrary, multiple measurements - using both satellites and tide gauges - show a rise in global sea levels. On average, since 1993, the sea has been rising by 3.18 mm per year, primarily as a consequence of thermal expansion due to warming, and to the melting of ice sheets. This rise contains marked spatial and temporal variations. Regionally and locally, changes may be greater or lower, affected not only by thermal expansion but factors ranging from local wind patterns to the mining of groundwater aquifers. In late 2010 and early 2011, sea levels underwent a sharp fall, a fact that was gleefully leaped upon by skeptics; but NASA researchers pointed out that 2010 saw a transition from a strong El Niño to “one of the strongest La Niñas in recent memory.”
9. The Planet Is Accumulating More Heat
The fact that the ocean is warming - and particularly the discovery of warming in the deep ocean - underlines an important point: the planet is accumulating more heat. Recently, skeptics have argued that an apparent reduction in increases in surface temperature somehow suggests that climate change is "slowing down" or even non-existent. But the heat trapped by greenhouse gases isn't just absorbed and radiated by land, and doesn't just heat the atmosphere. Satellite measurements of incoming and outgoing radiation, as well as studies that have combined measurements for land, ice, atmosphere and the ocean have all shown one unmistakable fact: the planet is accumulating heat, and doing so at a growing rate. When you consider all the heat building up in the entirety of our climate, global warming has actually accelerated over the past 16 years that deniers claim nothing is happening. So the heat build-up continues unabated. Not only is global warming not slowing down, it is increasing. When that "hidden heat" returns to the atmosphere, the impact will likely be felt strongly.
10. Extreme Weather Is More ... Extreme
Making a direct connection between climate change and extreme weather events is not straight forward. Weather, after all, is short-term and highly variable. There have always been and always will be storms and heatwaves. Climate scientists are careful not to scribe any specific weather event to global warming. However, climate creates the conditions in which weather takes place. Scientists have long suspected that a changing climate will make certain weather events more likely and others more extreme. Many researchers say we are increasingly seeing those predicted linkages show themselves.
A brand new study combined data from 73 sites around the world to show that temperatures today are warmer than they have been during 70-80 percent of the Holocene Epoch - the stretch of time, beginning about 11,300 years ago, since the last major Ice Age - and that, under all existing scenarios for different levels of greenhouse gas emissions, virtually every model shows temperatures will exceed the very hottest periods during that time. According to Candace Major of the National Science Foundation, "This research shows that we've experienced almost the same range of temperature change since the beginning of the industrial revolution as over the previous 11,000 years of Earth history -- but this change happened a lot more quickly."
Evidence is mounting that Greenland - the second-largest ice sheet in the world after Antarctica - is losing mass at an accelerating rate. Much of this loss is occurring along Greenland's edges, where rapidly-moving glaciers and ice streams are discharging more ice into the ocean than is being accumulated on the ice cap. To date, much of this ice loss has occurred in the southern part of the landmass, but it now appears that these losses are spreading to the northwest. Additionally, in July 2012, Greenland saw melting occur across approximately 97 percent of its surface ice.
Signs and Symptoms of Climate Change:
1. Carbon Dioxide Concentrations in the Atmosphere Are Increasing
2. The Hottest Decade on Record Keeps Changing
This is the first, key point. By analyzing air bubbles trapped in the ice of Antarctica and Greenland, scientists have been able to determine that over the past 650,000 or so years, atmospheric concentrations of carbon dioxide (CO2) varied between 180 and 300 parts per million (ppm), and in the years immediately prior to the Industrial Revolution in the mid-eighteenth century stood at approximately 280 ppm. Since then, however, that figure has steadily increased; by the time continuous monitoring began at Mauna Loa Observatory in Hawaii, it had climbed above 310 and is now closing in on 400.
Whether measured from land or from satellite, it is clear that global temperatures are increasing.
Averaged over all land and ocean surfaces, global mean temperatures have increased by approximately 1.33 degrees Fahrenheit (0.74 degrees Celsius) over the past century. More than half of this warming—about 0.72 °F (0.4 °C)—has occurred since 1979. Because oceans tend to warm and cool more slowly than land areas, continents have warmed the most (about 1.26 °F or 0.7 °C since 1979), especially over the Northern Hemisphere.