Sunday, September 29, 2013

New IPCC report warns of extreme climatic conditions, heatwave, uncertain monsoon and rise in salinity

By Our Representative
Expressing deep concern over the findings of the first assessment report of the Intergovernmental Panel on Climate Change (IPCC), the Climate Action Network, which is a network of 850 NGOs across the world, has said that it is more than certain than ever before that human activities are responsible for climate change. The first installment of the IPCC’s fifth assessment report was signed off by nations after its summary was negotiated line by line in Stockholm last week. Sanjay Vashist, director of Climate Action Network South Asia, said in a press release that though global warming “requires immediate action”, polluters have failed to make “equitable allocations and concrete actions” to fight the danger.
“The situation at hand requires immediate action. Climate impacts are continuing to mount, and we need to reduce pollution levels quickly and drastically,” he said, adding, “The IPCC report confirms that the planet is heating up, sea level rise is accelerating, the rate of Arctic sea ice retreat has doubled, the melting of glaciers and ice sheets is happening faster, and the oceans are acidifying. This report shows that the science on climate change is clear. The debate about who is responsible is over. It is time that governments take action to address this issue in an effective manner, and not through halfhearted efforts.
Representatives of the world’s governments will be in Warsaw in November for the major climate negotiations of the year. They should ensure this report is in their luggage and informs their negotiating positions. The report will be integral to countries who have been asked by the UN Secretary General Ban Ki Moon to bring “strong pledges” to a summit on climate action next September – ahead of the 2015 conference in France which is tasked with agreeing a global climate action plan.
The IPCC report warns, “There has been further strengthening of the evidence for human influence on temperature extremes. It is now very likely that human influence has contributed to observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century, and likely that human influence has more than doubled the probability of occurrence of heat waves in some locations. Global surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to 1850 to 1900.” It adds, “Warming will continue to exhibit interannual-to-decadal variability and will not be regionally uniform.”
The report says, “The global mean surface temperature change for the period 2016–2035 relative to 1986–2005 will likely be in the range of 0.3°C to 0.7°C. This assessment is based on multiple lines of evidence and assumes there will be no major volcanic eruptions or secular changes in total solar irradiance. Relative to natural internal variability, near-term increases in seasonal mean and annual mean temperatures are expected to be larger in the tropics and subtropics than in mid-latitudes.” It adds, increase of global mean surface temperatures for 2081–2100 relative to 1986–2005 is projected to likely be in the ranges from 0.3°C to 4.8°C.
Even as saying that warming is likely to exceed 2°C, the report says that “it is virtually certain that there will be more frequent hot and fewer cold temperature extremes over most land areas on daily and seasonal timescales as global mean temperatures increase. It is very likely that heat waves will occur with a higher frequency and duration. Occasional cold winter extremes will continue to occur. Extreme precipitation events over most of the mid-latitude land masses and over wet tropical regions will very likely become more intense and more frequent by the end of this century, as global mean surface temperature increases.
It further says, “Globally, it is likely that the area encompassed by monsoon systems will increase over the 21st century. While monsoon winds are likely to weaken, monsoon precipitation is likely to intensify due to the increase in atmospheric moisture. Monsoon onset dates are likely to become earlier or not to change much. Monsoon retreat dates will likely be delayed, resulting in lengthening of the monsoon season in many regions.”
The report points towards the danger of rise in salinity levels in areas which are subject to high evaporation. It says, “It is very likely that regions of high salinity where evaporation dominates have become more saline, while regions of low salinity where precipitation dominates have become fresher since the 1950s.” It adds, “It is likely that anthropogenic influences have affected the global water cycle since 1960. Anthropogenic influences have contributed to observed increases in atmospheric moisture content in the atmosphere, to global-scale changes in precipitation patterns over land, to intensification of heavy precipitation over land regions where data are sufficient, and to changes in surface and subsurface ocean salinity.”
In separate statements, participants in the IPCC working groups expressed grave concern over the prevailing scenario. “Observations of changes in the climate system are based on multiple lines of independent evidence. Our assessment of the science finds that the atmosphere and ocean have warmed, the amount of snow and ice has diminished, the global mean sea level has risen and the concentrations of greenhouse gases have increased,” said Qin Dahe. Added Thomas Stocker,“Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions."
“Global surface temperature change for the end of the 21st century is projected to be likely to exceed 1.5°C relative to 1850 to 1900 in all but the lowest scenario considered, and likely to exceed 2°C for the two high scenarios,” Stocker further said, adding, “Heat waves are very likely to occur more frequently and last longer. As the earth warms, we expect to see currently wet regions receiving more rainfall, and dry regions receiving less, although there will be exceptions”.
Projections of climate change are based on a new set of four scenarios of future greenhouse gas concentrations and aerosols, spanning a wide range of possible futures. “As the ocean warms, and glaciers and ice sheets reduce, global mean sea level will continue to rise, but at a faster rate than we have experienced over the past 40 years,” said Qin Dahe. The report finds with high confidence that ocean warming dominates the increase in energy stored
in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010. Stocker concluded: “As a result of our past, present and expected future emissions of CO2, we are committed to climate change, and effects will persist for many centuries even if emissions of CO2 stop.”

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