We and our planet are going to be in for serious and probably irreversible changes -- only 40 years from now.
The preceding sections give us the following picture for our planet in the year 2050, under the "business as usual" response -- the response favored by global warming skeptics.
1) In our straightforward projection, human activities have increased the atmospheric carbon dioxide levels to twice the pre-industrial level. This is twice the maximum interglacial levels recorded over the last 1.3 million years. An increase of CO2 of this magnitude has had a large, undeniable effect on the temperature of the planet.
2) From the CO2 increase alone, the global average surface temperature of our planet has increased 2.5 degrees Centigrade (4.5 degrees Fahrenheit) by 2050. This is relative to the 1910 mean global minimum. Relative to the average 1980-99 global mean (the reference level in the tipping point table) the global rise would be about 2.0 degrees. A rapid rise of this magnitude has had many effects on the Earth's non-linear, highly driven weather system.
3) There has been an increase in storms and in extreme weather of all kinds. The effects on storms have included increased power in cyclones and hurricanes. Coupled with a rise of about a meter in sea level, storm surges have caused extensive damage to coastal areas around the world. Several island nations have ceased to exist, as have some low-lying urban regions in Florida, the Gulf region and the Atlantic coast, to mention only the U.S. areas affected.
4) The temperature rise in the Arctic has been about twice that of the global mean. The permafrost has been melting at a huge rate, leaving the tundra scattered with shallow lakes. Enormous quantities of methane have come from these lakes and from the bottom of the warming Arctic Ocean, enough to cause an increase in the rate of rise of the global mean temperature. This effect alone could potentially contribute another 0.5 degrees of warming by 2050.
5) The Greenland ice sheet is well into its melting, resulting in a total sea level rise of more than a meter (39") causing extensive damage to coastal areas, including shoreline erosion, loss of wetlands, agricultural areas and living areas.
6. There has been extensive disruption of agriculture around the world due to climate change, including long-term droughts in some areas and increased flooding and storm damage in others. While there have been some new opportunities for food production in areas that were formerly too cold or too dry, these opportunities have not been sufficient to make up for losses elsewhere.
7) The summer Arctic sea ice is now completely gone, resulting in further changes to the Northern climate and ecosystems.
8. With a 2.5 degree rise in global temperature, the Earth now stands on the precipice of several additional, potentially catastrophic tipping points. These include: melting of the West Antarctic ice sheet, the diversion of the Atlantic circulation, the increase in strength of the El Nino phenomena, and the loss of most of the Amazon and boreal forests.
It is clear that it would be wise to avoid these additional catastrophes by an immediate halt to CO2 production -- but with most of the world's people on the brink of starvation, their immediate survival is more important to them than making sacrifices by stopping the use of fossil fuels, trees for firewood for cooking, etc.
After forty years of business as usual, it is now too late to make needed changes. The world, its peoples and resources strained to the breaking point, can now only continue to careen forward, straight into the teeth of these new, catastrophic changes.
Our forecast is worse than that of the IPCC
As mentioned in the introduction, the International Panel on Climate Change (IPCC) has been forced to produce cautious, conservative reports. Their 2007 report gave the projections above for the surface temperature through the rest of the century. Our projection of a temperature rise of 2 to 2.5 degrees (relative to the baseline of this graph) is clearly at the very upper range of their forecasts. Why?
The IPCC forecasts make the unwarranted assumption that nations and people will try to do the right thing, and hold back some of their carbon dioxide emissions. Equivalently, they assume that the world's economy will rise at a slightly lower rate than the rate that we have derived by simply fitting the most recent CO2 rise.
We have not made any such rosy predictions. We have just extrapolated the present trends forward without any such decrease in rate. We used the rate that fits the CO2 data, a 2.2% annual growth rate in CO2 production, a rate that is securely determined. You can even directly see from the data in the graph above (the black line) that the IPCC would get the same answer that we did if they made the same "business as usual" assumption.
We will stick by our prediction. The mean global temperature will be up more than 2 degrees by 2050. We will put money on it.