I TRUST THE scientific process. I think it is humanity’s best way of understanding the natural world, for acquiring new knowledge and integrating or correcting previous knowledge in a logical way.

I trust the scientific theory of anthropogenic climate change.

Just like the theory of evolution or the theory of gravity, the scientific theory of climate change has a robust and convincing body of scientific evidence behind it. Dating back nearly two hundred years and drawing from multiple lines of scientific research, scientists have been monitoring our planet’s climate and informing us of the rapid changes that are occurring, in large part, because of human activities.

The scientific conclusions supporting climate change have been thoroughly examined, tested, and supported by so many independent observations and results that the likelihood of them being found wrong is now inconceivable.

Climate change denial

Unfortunately a small minority of readers will not agree with this synopsis. Some people who read this article will reply by presenting some opposing hypothesis that claims anthropogenic climate change is not occurring or, at worst, is insignificant or benign. Unfortunately they are wrong.

In my experience, there are two types of people who have difficulty accepting the scientific conclusion of climate change.

The first group simply doesn’t understand the science. This is perfectly understandable. For many of us, science can be a distant and abstract concept that appears to have little or no bearing on our day-to-day lives.

The second group however is different; they have a conservative ideology that doesn’t allow them to accept the scientific conclusions of anthropogenic climate change. Research suggests that “confident”, conservative, white males contribute significantly to the high level of climate change denial in America. It is this group I believe will probably make the most noise in response to this article.

Extreme weather

The year 2012 will be remembered as the year of climate change warning.

Last year, scientists discovered that the Western Antarctic ice sheet was warming twice as fast as it was expected to, placing west Antarctica among the fastest-warming regions on Earth.

Snow cover in Europe and Asia last summer was the lowest since satellite observations began 45 years ago.

In July, NASA satellites observed unprecedented Greenland ice sheet surface melt, with an estimated 97 per cent of the ice sheet surface having thawed by 12 July. In fact, Antarctica and Greenland combined are now losing ice mass three times faster than they were 20 years ago.

In September, scientists from the National Snow and Ice Data Center said Arctic sea ice had reached the lowest extent since records began in 1979 – a drop of at least 45 per cent.

In October, Superstorm Sandy wreaked havoc on parts of the US East Coast – killing 125 people in the United States – and was blamed for about $62 billion in damage and other losses.

The year also saw persistent wet weather for the UK, resulting in total rainfall just 6.6 mm short of the 2000 record. In fact, four of the top five wettest years in the UK have happened since 2000.

This year

Australia started 2013 with new record 50 °C temperatures and over 100 wild bush fires.

Last week 13 US government agencies collectively published the third National Climate Assessment Report. This 1,000-page report, the work of the more than 300 government scientists and outside experts, was unequivocal on the human causes of climate change, and on the links between climate change and extreme weather. The report also highlighted that the steps taken by government to reduce emissions are “not close to sufficient” to prevent the most severe consequences of climate change. It is a story mirrored by governments all around the world.

This year will also see the United Nations Intergovernmental Panel on Climate Change (IPCC) publish their first Working Group report of the Fifth Assessment Report (AR5). AR5 updates the last IPCC report AR4, which was published back in 2007 with the most up-to-date scientific research on climate change.

In expectation of the IPCC report, New Scientist ran a cover story in November: the story listed seven important scientific updates on the AR4 report and concluded the story with a comment from Steven Sherwood, an atmospheric scientist at the University of New South Wales. Sherwood said that “if humanity fully ‘develop’ all of the world’s coal, tar sands, shales and other fossil fuels we run a high risk of ending up in a few generations with a largely unliveable planet.”

Understanding the math

I started this article by saying that I trust the scientific method. German scientists calculated that from 2000 and 2050 humanity should emit no more than 886 gigatons of carbon dioxide (GtCO2) in to the atmosphere to stay below 2°C of global warming — anything more than that runs the risk of catastrophe for life on earth. In the last 10 years we have used 1/3 of that total budget leaving 565 GtCO2 over the next 35 years. We only have to do the math.

The political problem with this calculation however, is that humanity actually has access to 2,795 GtCO2 of known fossil fuel reserves, five times the safe amount to burn. So the problem for all of us is simple.

Do we burn more that 565 gigatons of carbon between now and 2050?

If the answer is yes, science knows what the outcome will be.

If the answer is no, we need to think and act very differently to figure out how we might achieve this goal.

This year the Irish government will publish a long-awaited climate change bill. At the moment it is understood they are considering a bill that is not based on a CO2 budget approach. Any future climate change legislation must have science-based targets for CO2 reduction if it is to work – because a law without targets is like a football match without goals.

Gavin Harte has been a spokesperson on environmental and sustainability issues in Ireland for many years. He has worked as the national director of An Taisce and was the founder and developer of Ireland’s first eco-village in Cloughjordan Co Tipperary and now runs ESD Training, his consultancy for Education on Sustainable Development.