04/04/2014 09:56 BST | Updated 04/06/2014 06:59 BST

Climate Change: Apocalypse Now and the Trillion Dollar Challenge

You may have seen apocalyptic headlines in the press recently. Headlines warning that climate change will be felt 'on all continents and across the oceans', and that the world faces a 'violent, sicker, poorer future'.

Well stay with me, and I'll explain why we might not be facing 'apocalypse now'.

The headlines came from the latest report from the Intergovernmental Panel on Climate Change, which every six or seven years produces landmark reports on climate change. The reports - the current one is the fifth assessment report that the IPCC has done, called AR5 in the jargon - are so big that they are broken up into sections: three working group reports, and a final one which draws all the sections together.

The first part of this IPCC report was released last September. Looking at the physical science basis for climate change, it found that scientists are more certain than ever that global warming is getting worse and that humanity is to blame for rising temperatures. Concentrations of greenhouse gases like carbon dioxide have increased to levels not seen for over 800,000 years and the world is on track to see global temperatures rise past 2°C before the end of this century, the so-called maximum 'safe' level of warming that governments around the world have committed to.

In fact, scientists said that the world is likely to face warming in the range of 0.3C to 4.8°C by the end of the century, which may be a conservative estimate. Others, like the World Bank, argue that we're currently on track for a 4°C world. These amounts might not sound like much but globally, they would have huge impact - to put it into context, the difference in global temperatures between now and the last ice age is just 5°C.

The Bank warned of a world marked by "extreme heat-waves, declining global food stocks, loss of ecosystems and biodiversity, and life-threatening sea level rise", a theme taken up by the IPCC's second report, released last month in Japan. Looking primarily at the impacts of climate change, it was this report which delivered the truly chilling headlines about the effect a warming climate will have.

Deaths from sea-level rise related flooding. Famine caused by temperature and rainfall changes, especially in developing countries. Deadly heat-waves increasing. Precious ecosystems, such as coral reefs and arctic ecosystems, facing collapse. Major infrastructure failures because of extreme weather. Declining crop yields and decreasing freshwater availability hitting food production. Oceans acidifying, threatening sensitive marine habits and food supplies.

The impacts could combine, warned the report, to slow economic growth globally and increase poverty, and to even spark conflicts over increasingly scarce resources, which is one of the reasons why military planners take the threat of climate change so seriously.

So, the end of the world is nigh, and it might be tempting for some to say that we should give up now: we can't stop climate change, so let's just try to hunker down and ride it out.

I'm not one of them.

Because although climate change has the potential to undo all of the good work we've done at WWF over the last fifty years, I know we have the knowledge and power to stop climate change and avoid some of the worst consequences right now. And this is where the next section of the IPCC report comes in.

Due to be published soon in Berlin, the third section looks at mitigation of climate change and is expected to focus squarely on an issue that WWF is campaigning on right now around the world. We expect the IPCC to say that the main way of tackling climate change is by decarbonising our energy systems - that is, by stopping the use of the most polluting fossil fuels and switching to clean renewable energy instead.

And money is the key. Only by switching huge amounts of investment away from fossil fuels and into renewables will we have a chance of stopping dangerous climate change. And the numbers are huge. Right now, there is enough money invested in existing fossil fuel reserves - including your money and mine, via banks, savings and pension funds - to comfortably bust the world's carbon budget. In other words, we have two choices: either those fossil fuels are burnt, driving massive global warming, or they are not and that investment is simply a huge bubble in the global financial system (the so-called 'carbon bubble').

On the investment side, the challenge is daunting but manageable: the sustainable investment organisation Ceres recently calculated that in total $36 trillion in global investment in clean energy will be required by 2050, to keep global temperatures rises below 2°C, which means that "the world needs to invest an average of $1 trillion per year in clean energy for the next 36 years to avoid climate catastrophe". Currently, we're a long way off that: in fact, global investment in renewable energy fell 12 percent in 2013 to $254 billion.

This is why WWF is running a global campaign, Seize Your Power, calling on calling on financial institutions including major sovereign wealth funds, pension funds and multilateral development banks to significantly increase their funding of renewable energy and cut funding to fossil fuels as a key means of tackling climate change.

Because the messages from the IPCC couldn't be clearer. Climate change is a huge risk which the world isn't doing enough to tackle. We still have time, although the window of opportunity is closing rapidly. And changing our energy sector is crucial. We must quit fossil fuels and switch to clean renewable energy. As I said: we have the knowledge and power to stop climate change - we just need to seize it.