When one considers the complexity of climate modelling, the surprise to me is that 97% of climate science papers agree global warming is human-induced. A survey conducted by Skeptical Science reports the findings thus:
"A new survey of over 12,000 peer-reviewed climate science papers [between the years1991 and 2011] by our citizen science team" has found a 97% consensus among papers taking a position on the cause of global warming in the peer-reviewed literature that humans are responsible."
As computing power increases, the predictions will become more accurate. Incorporating climate data and observations as they become available into the model helps refine the results and predictions.
There are many factors that cause short term variations in global warming. The Royal Society and the US National Academy of Sciences list some of them and in so doing give us an insight into the complexity of climate modelling:
"Even as CO2 is rising steadily in the atmosphere, leading to gradual warming of Earth's surface, many natural factors are modulating this long-term warming. Large volcanic eruptions increase the number of small particles in the stratosphere that reflect sunlight, leading to short-term surface cooling lasting typically two to three years, followed by a slow recovery. Ocean circulation and mixing vary naturally on many time scales, causing variations in sea surface temperatures as well as changes in the rate at which heat is transported to greater depths. For example, the tropical Pacific swings between warm El Niño and cooler La Niña events on timescales of two to seven years. Scientists know of and study many different types of climate variations, such as those on decadal and multi-decadal timescales in the Pacific and North Atlantic Oceans, each with its own unique characteristics. These oceanic variations are associated with significant regional and global shifts in temperature and rainfall patterns that are evident in the observations."
These variations are put in context thus:
"The magnitude and timing of these changes will depend on many factors, and slowdowns and accelerations in warming lasting a decade or more will continue to occur. However, long-term climate change over many decades will depend mainly on the total amount of CO2 and other greenhouse gases emitted as a result of human activities."
Fossil fuel is stored energy that took millions of years to accumulate. At the start of the industrial revolution we began releasing this energy at an enormous rate to power our civilization. Energy accumulated over millions of years is being released in a few hundred years. It should surprise no-one that such massive intervention in the carbon cycle produces global warming.
It is high time we accepted the science climate change is real and man-made and started to implement energy saving measures in everything we do. We need to embrace renewable energy and in so doing drastically cut our emissions of greenhouse gases. Only through this can we limit the devastation that will result if global warming is to exceed substantially the critical threshold of 2C.
In fact the latest IPCC report makes it clear that whatever we do from now on, we are likely to go beyond 2C. That does not mean we should do nothing, as the worst effects of warming extreme weather conditions and rises in sea levels are directly dependent on the extent of global temperature rise above 2C.
Nicholas Stern, Chair of the Grantham Research Institute on Climate Change and the Environment at the LSE, in a recent article in the Guardian (February14, 2014), comments on his 2006 review on the economics of climate change thus:
"In fact, the risks are even bigger than I realised when I was working on the review of the economics of climate change for the UK government in 2006. Since then, annual greenhouse gas emissions have increased steeply and some of the impacts, such as the decline of Arctic sea ice, have started to happen much more quickly. We also underestimated the potential importance of strong feedbacks, such as the thawing of the permafrost to release methane, a powerful greenhouse gas, as well as tipping points beyond which some changes in the climate may become effectively irreversible."
The 2006 review makes the point that countries don't have to choose between economic growth and taking action to arrest climate change. The review tells us that:
"Without action, the overall costs of climate change will be equivalent to losing at least 5% of global gross domestic product (GDP) each year, now and forever. Including a wider range of risks and impacts could increase this to 20% of GDP or more, also indefinitely. The Review proposes that 1% of global GDP per annum is required to be invested to avoid the worst effects of climate change. In June 2008, Stern increased the estimate for the annual cost of achieving stabilization between 500 and 550 ppm CO2e to 2% of GDP to account for faster than expected climate change."
Thus, taking action to stabilize climate change is cheaper than doing nothing. Moreover, such actions energy saving measures and investment in renewable energy are the only way of having sustainable economic growth.
The science is "unequivocal'; climate change is real and human-induced. Embracing the renewable energy route will usher in a new industrial revolution that will be in harmony with our environment, and in so doing will safeguard the future of humanity.