Malebranche says the industrial era has given birth to a new phenomenon: human activity changing the make-up of the atmosphere. As a result, she believes global warming is "now an unequivocal fact".
An Intergovernmental Panel on Climate Change (IPCC) report concludes that global warming is caused by a rise of greenhouse gases in the atmosphere. Thus as long as emissions from humans continue to rise, so too will the greenhouse effect.
The speed of warming per decade in the last fifty years has "almost doubled compared to that of the previous hundred years," says Malebranche. Analysing the concentration of CO2 in the atmosphere reveals the actual impact of humans on climate change, she reveals, indicated by: around 379 parts per million (ppm) in 2005 compared to the natural variations of between 180,000 – 300,000 ppm in the last 800,000 years.
The IPCC report says it is "highly probable" that humans play a role in climate change, while Malebranche argues that if the Greenland ice sheet melts, it will cause global sea levels to rise by seven metres.
The author uses recent studies to show how the last decade was the hottest ever recorded, while the average speed of warming "has practically doubled".
One of the effects of climate change is the warming of the seas, forcing species and organisms to move to more northerly waters, says Malebranche. She adds that human activity since 1850 has led to the acidification of the oceans.
Despite current efforts to reduce carbon emissions, the global average temperature is set to rise, claims the author. Even if the ice sheets do not melt, sea levels are set to rise by about half a metre by 2100, which would put coastal areas in Bangladesh and the African and Asian deltas under threat, she adds. This will then affect soil salinity, argues Malebranche, which will negatively influence about 1.2 billion people.
The resultant drop in water availability in arid regions will affect a sixth of the world's population and will likely lead to mass population migrations, which will only get worse as the planet's population increases, says the author. Additionally, if global temperatures rise by 2.5°C then around 30% of known species will become extinct, while if it rises by over 3.5°C then up to 70% could become extinct, she claims.
There is a clear North/South divide, and those countries who are not capable of facing the challenges of climate change will be the most vulnerable, believes Malebranche. According to the author, IPCC experts have been encouraging decision-makers to think in terms of long-term solutions, such as technology transfer to the poorer nations, to help them prepare for the years ahead.
The IPCC has concluded that to prevent global average temperatures reaching 3°C within a century, greenhouse gases must not exceed 550 ppm, meaning a cut in greenhouse gas emissions by half is required by 2050.
Malebranche concludes by suggesting lifestyle and behaviour changes are likely to limit climate change in the long term, but that for this to happen, people will need to be educated to force a change in attitudes.
