Global Warming

The Fourth Assessment Report (4AR) of the Intergovernmental Panel on Climate Change (IPCC), released in February 2007, provided the strongest statement yet that global warming (or climate change) is (1) real, (2) is going to lead to significant adverse impacts within the next century, and (3) is being driven by human activity. The 4AR is the latest iteration of the IPCC's flagship summary of the scientific basis of climate change and its impacts (the previous one was in 2001) and concludes:

1. Human influences on climate are "very likely" detectable in the observational record (meaning >90 percent chance; up from 66 percent in the previous report);
2. Global temperatures are likely to rise by between 1.1 and 6.4 degrees Celsius by 2100 (1.4 to 5.8 degrees Celsius in the previous report); and
3. Sea levels are likely to rise by between 0.18 and 0.59 meters by 2100 (the upper limit reduced from 0.88m from the previous report).

What these key conclusions mean in real terms is difficult as much of the impact will depend on where you live and your capacity to adapt. The ranges in 2 and 3 above also depend on what action humanity takes to tackle this challenge. Much of the research to date doesn’t provide a complete picture of what temperature rises of 1 or 6 degrees Celsius means.

Environmentalist and climate change author Mark Lynas has researched this to provide a holistic view of what each degree of additional warming means for life on Earth. His book Six Degrees paints a near-apocalyptic picture of what awaits humanity unless we act very soon (preferably immediately) to move our economy away from its reliance on carbon-based energy. The former chair of the IPCC, Professor Bob Watson has been championing "mitigate for two degrees, prepare for four" in his post-IPCC role in the Millenium Ecosystem Assessment, a landmark UN study, published in 2005, that looks at the total human impact on the Earth’s natural systems.

Much of the political discussion revolves around the likelihood of two degrees of warming by 2100. That doesn’t sound like much—however, this is not the same everywhere on our planet and it does not mean that we simply add two degrees on to the temperature wherever in the world we may be. Two degrees means:

• acidification of the world’s oceans, endangering much of the marine food chain;
• summer heatwaves of increasing frequency, duration, and intensity. It is likely that every second summer on average will endure severe heat waves (like the 2003 heatwave in Europe that resulted in some 30,000 deaths);
• more frequent and longer incidences of drought, adversely affecting crop and food production in many parts of the world;
• the combination of severe heatwaves and drought is likely to result in more frequent occurrences of wildfires (such as the 2003 and 2009 Mediterranean wildfires);
• desertification of mid-west United States, extending from southern Canada through to Texas, as well as the expansion of current desert areas of Africa, Asia, and Australia;
• the disappearance of much of the glaciers in South America and Asia, meaning that hundreds of millions of people (possibly billions) will lose their sources of fresh water—threatened or wiped out;
• Greenland will tip into irreversible melt, accelerating sea level rise which is by this stage already threatening low lying countries such as Bangladesh and likely to have already displaced many Indian and Pacific Island communities;
• the Arctic Ocean will be ice-free in summer, causing the extinction of polar bears, walruses, and other ice dependant marine mammals;
• cause the mass extinction of perhaps as much as a third of animal and plant species worldwide (the greatest mass extinction since the dinosaurs disappeared some 65 million years ago).

This isn’t science fiction postulation—this is published research in peer-reviewed scientific journals like Nature and Science. Often, conclusions have been drawn based on analysis of past changes in the paleoclimatic record and complex modeling to determine the impact of such changes today. It is grim stuff and the only IPCC scenario with the best estimate that avoids this (see p13 of the Summary for Policy Makers of AR4) is the B1 scenario. This assumes a global population that peaks around 2050 and declines thereafter, with rapid change in economic structures towards a service and information economy, with reductions in material intensity and wholesale introduction of clean and resource-efficient technologies.

Is this going to happen? Possibly. Is it likely soon? No. The opening salvoes in the policy efforts to combat carbon emissions fall woefully short and the political realities in democratic societies mean that the hard decisions are unlikely to be made. The Waxman-Markey Bill in the US and the Carbon Pollution Reduction Scheme (CPRS) legislation in Australia face a difficult path to become law and both have already been severely watered down to help negotiate the necessary votes to become law. In Australia, the CPRS legislation was rejected in the Senate by two parties with diametrically opposed philosophies—one for being too expensive for business (Liberal) and because they don’t believe that climate change is real (Nationals, the Liberal’s political partners), and the other because it doesn’t do anywhere near enough to achieve its policy objective (Greens). Getting every country to pass legislation to reduce carbon emissions by 80 percent by 2050 is going to require a paradigm shift that will only be prompted when the worst impacts are felt. By then, according to scientists, it will be too late.

Anything less than this means that the more adverse scenarios, the four to six degrees of warming are likely if not unavoidable. And this is perhaps why Professor Watson suggested preparing for four. Four degrees is towards the upper end of the IPCC estimates, however, the AR4 estimates were prepared on research that was at best two years out of date by 2007 and carbon emissions have been tracking at or above worst case scenario paths.

The problem with greenhouse gas emissions is that they do not have an immediate impact. Even if we were to stop these emissions tomorrow, the greenhouse gases we have already pumped into the atmosphere will continue to have a radiative effect for centuries. According to AR4, this would still lead to between 0.3 and 0.9 degrees Celsius of warming by 2100. In a way, it is really only delaying the inevitable (we would hit that two degrees mark some time in the 23rd century instead of at the end of the 21st). The other problem is that the Earth is a chaotic and complex system and there are impacts that could trigger further impacts, mostly adverse and which lead to further acceleration of changes. As an example, melting permafrost releases methane into the atmosphere. Methane is a potent greenhouse gas and could drive further warming.

Four degrees essentially means a different planet. Professor Neil Adger, a climate change expert with the Tyndall Centre for Climate Change Research in Norwich, England said:

"At four degrees, we are basically into a different climate regime. I think that is a dangerous mindset to be in. Thinking through the implications of four degrees of warming shows that the impacts are so significant that the only real adaptation strategy is to avoid that at all cost because of the pain and suffering it is going to cost." He added, "There is no science on how we are going to adapt to four degrees warming. It is actually pretty alarming."

If you are the kind of person who grasps ideas better from a visual perspective, here is what four degrees of warming mean. In reality, four degrees cross many of the tipping points that so concerned scientists in the field. It is like a massive uncontrolled science experiment and those tipping points could easily lock in changes of six degrees and beyond. Six degrees is beyond our society’s capacity to adapt and would very possibly lead to the end of life as we know it. And that is about as bad as it can get.

About Author:

Joseline Burns is a teacher and PhD writer at one of the best essay writer services with over nine years of experience in the educational field. She has been writing and editing content for social media, led her own blogs for five years. She has many hobbies and she can write about everything. Her main goal—to help people with self-development, to teach them to look at the situation from different sides. Also, she is a big fan of fantasy movies, science, and psychology.