What if the IPCC projections for the rise in the Earth’s temperature were wrong? Well, if the temperature does not rise much further, everyone will be relieved, but what if the temperature rise is much greater than predicted? In the article below, Paul Roth, DEA Member, reviews for us the evidence that warming is occurring faster than expected.
In a paper published in NatureGeoscience Aug 9 2009, Global warming in the Cenozoic era 55 million years ago was studied. In the Palaeocene–Eocene Thermal Maximum period, there was a massive injection of carbon into the ocean–atmosphere system, but the resulting climatic warming was much greater than expected from the modelled rise in atmospheric carbon dioxide alone. Temperatures rose by 5–9 °C whereas modelling shows that only 2-3 degree rise was predicted. The author concluded that feedback mechanisms released additional carbon dioxide and methane. Since there was no ice on the planet at that time possible operative feedback mechanisms included methane emissions from swamplands and permafrost and increases in atmospheric moisture, biogenic aerosols and cloudiness.
Returning to the present time, Paul Roth writes
An increasingly large amount of peer-reviewed research, published since the IPCC 4th Assessment Report was released in 2007, shows that global warming is happening right now, and that it is quicker than predicted just 2 years ago.
The evidence for this statement is from many areas. Some of the areas showing change are shown below.
* Multiple ecosystems, in multiple locations, now show the effects of global warming. Examples include the timing of plant flowering, animal breeding, and lake thawing.
* Higher ocean surface temperatures in Pacific and Atlantic oceans; Atlantic hurricane-formation zones leading to stronger cyclones are definitely related to anthropogenic warming.
* Ocean acidification is happening rapidly, as a result of CO2 in large amounts being dissolved in sea water. This will have massive changes on marine ecosystems and also food security for many nations.
* Expected sea-level elevation over the next few decades will be greater than that predicted in 2007. It will probably increase a metre or more, according to recently published research.
* The accelerated melting of the ice sheet in Greenland that started in 2004 has been definitely linked to climate change.
* The West Antarctic Ice Shelf has undergone rapid melting over the last 10 years and has suffered 10 major ice shelf collapses over that time.
* Sea-ice in the Arctic is disappearing much quicker than previously estimated, and it is almost a given that this area will be ice-free in summer within a few decades.
* Thawing of the boreal permafrost is much speedier than recently calculated, and is expelling a lot more greenhouse gases than expected.
The global warming that is now occurring is going to extend for multiple centuries even after all human-released greenhouse gas escape ceases. This is due to the significant inertia that exists in the climate and the delayed decay of carbon dioxide from within the environment (around 25% remains for greater than 5000 years).
It remains to be seen whether we will work as one to avoid the worst problems of global warming before we pass an important tipping point that might kick off extreme global warming.