More Evidence that Humans Cause Rise in Temperature - Climate Council
1 October 2013 at 10:13 am
The Climate Council, the newly formed, independent environment Not for Profit, has released its summary of The Intergovernmental Panel on Climate Change (IPCC) report, which has found that scientists were now more certain that increasing global temperatures since 1950 were caused primarily by human activities.
According to the Climate Council’s companion report, there’s more evidence that humans cause a rise in the earth’s temperature.
The Climate Council says there were four “key messages” in the first part of the IPCC report released last week.
“1. Our understanding of the climate system has only continued to strengthen in the last six years,” the summary paper states. “Ocean and air temperature are rising, mass from glaciers and ice sheets is being lost, and sea level is rising.
“2. Scientists are more certain than ever that increasing global temperatures since 1950 have been caused primarily by human activities.
“3. A warming climate is increasing the frequency and severity of many extreme weather events and is changing rainfall patterns, creating risks for human well-being, the economy and the environment.
“4.Stabilising the climate system will require substantial and sustained reductions of carbon dioxide (CO2) emissions. We will have to decarbonise the economy.”
The summary states that according to the IPCC report, the global average air temperature has risen by about 0.85C since the start of the 20th century and has continued to rise.
“The period 2001–2010 was the hottest decade on record. The ocean absorbs over 90 per cent of the extra heat trapped by the rising concentration of greenhouse gases, vastly more than all of the other components of the climate system combined,” the summary paper states.
“As a result, the ocean has warmed since the 1970s, the period with widespread ocean observational systems, with much of the heat stored in the upper 700 metres.
“More recently, observations show warming in the deep ocean below 3000 metres in the North Atlantic and Southern Ocean.
“Glaciers and ice sheets around the world are shrinking and losing mass. The combined rate of mass loss from the large polar ice sheets on Greenland and Antarctica has risen to about 350 billion tonnes per year for the period 2002–2011.”
The paper also states that the sea level has risen by 19cm over the 1900–2010 period, and at an increased rate over the period since 1993.
“The rate of sea-level rise over the last century is unusually high in the context of the last 2,000 years,” it stated.
The summary also stated that the atmospheric concentration of carbon dioxide (CO2), the most important long-lived greenhouse gas, has increased by 40 per cent since the beginning of the industrial revolution.
“The concentrations of other important greenhouse gases, such as methane and nitrous oxide, have also increased significantly as a result of human activities,” the summary stated.
It also stated the IPCC report had confirmed and strengthened the key findings of the 2012 IPCC Special Report on extreme events.
This included: many extreme weather events have become more frequent and more intense since 1950; Many regions, including Australia, have experienced longer and more intense heatwaves; a trend toward heavier rainfall events; the incidence of coastal flooding has likely increased since 1970, exacerbated by rising sea levels.
“If emissions continue to increase unabated, sea level could rise by nearly 1 m by 2100, compared to its average level between 1986–2005,” the summary stated.
“Sustained warming could eventually lead to the loss of the entire Greenland ice sheet, with a long-term rise in sea level of up to 7m.”
The summary also stated that stabilising the climate system would require substantial and sustained reductions of CO2 emissions.
“If emissions continue to track at the top of the IPCC scenarios, global temperature could rise by up to 5.4°C by 2100, relative to pre-industrial levels,” the summary stated.
“Limiting global temperature increase to 2°C requires limiting total post-industrial carbon emissions from all sources to 1000 billion tonnes.
“By 2011 about half of this budget had already been emitted.
“However, the available carbon budget may actually be smaller when the projected warming effects of non-CO2 greenhouse gases and the possible release of methane from melting permafrost and ocean sediments are considered."