Typhoon Haiyan, which has so ravaged the Philippines, reminds us how vulnerable parts of the world are to the vagaries of weather. Although climate change is not believed to have caused the typhoon, similar levels of devastation will become commonplace if nothing is done to slow the warming of the planet.
Time is running out. In September, the Intergovernmental Panel on Climate Change (IPCC) confirmed that the warming of the global climate system is "unequivocal," and that the influence of human activity is "clear." At current rates of change, the world is unlikely to be able to prevent global temperatures rising by more than the IPCC's target of 2°C by the end of this century.
Decision-makers at the United Nations Warsaw Climate Change Conference this month must therefore send a clear signal to governments around the world that future growth must be environmentally sustainable. They should also affirm that financing this transformation is best achieved by bringing together public- and private-sector investors. The changes the world needs will cost no more in the long run than if we carry on as usual - and may save our planet.
If a sign of things to come were needed, one would do well to look at Africa, which is already highly vulnerable to climate variability. Further volatility could be ruinous. Two-thirds of the continent is desert or drylands, and three-quarters of its agricultural drylands are significantly degraded. The Sahara Desert is expanding: Lake Chad, for example, is now one-tenth of its size a half-century ago. The worst conditions are in the Horn of Africa and the Sahel, where drought and famine have left more than one million children at risk of severe malnutrition.
Africa emits a mere 4% of the world's CO2, but it suffers most from its ill effects. That said, Africans bear some of the blame, too: for example, four million hectares of African forest disappear annually - twice the global rate of deforestation.
Few would argue that Africa's priority must be to meet the most basic needs of a population that is set to double by 2050, reaching two billion. Despite enjoying roughly 5% average annual GDP growth for many years - the continent-wide economy has tripled in size, to more than $2 trillion, since 2000 - Africa still has some 600 million people living on less than two dollars a day. As a result, it is a long way from meeting the UN Millennium Development Goals in health and education.
But Africa's growth imperative should not exclude an environmentally friendly approach. Indeed, several countries - including Kenya, Morocco, Mozambique, Rwanda, and Sierra Leone - have put green growth at the heart of their national development policies. That is a wise move: Africans live close to the land, and their natural resources can help strengthen their human capital. With half the population under the age of 25, governments must take care in managing this enormous economic potential.
Recent research suggests that up to a half-million green jobs could be created in South Africa alone - more than in the country's entire mining sector. Nevertheless, renewable energy is still viewed in some quarters as being too expensive - more an act of faith than a commercial decision. I was part of the UN Secretary-General's advisory group that in 2010 estimated that $100 billion annually would be required for ten years to support effective climate policies in developing countries.
But, while most of the money will come from government, Africa's experience shows that it is possible to attract private funding, too. Last year, the African Development Bank (AfDB) raised $2.2 billion to address climate change, 50% more than in 2011. It can leverage $4 for every $1 entrusted to it. In 2012, more than 90% of the newly approved energy projects funded by this money were green. Public-sector funding then paved the way for private capital at, for example, the world's largest solar facility in Ouarzazate, Morocco, and the pioneering geothermal project in Menengai, Kenya. The Menengai project increases Kenya's generation capacity by one-fifth (enough to supply energy to 500,000 households) and reduces CO2 emissions by two million tons (equivalent to a year's emissions from a half-million cars).
The most forward-thinking private investors are now on the hunt for any green investment that offers a reasonable yield. In October, the AfDB launched its inaugural "green bond," which raised $550 million from around the world within 24 hours. Investing in a green future can clearly be a commercial venture as much as a social or moral obligation. And that means there is no reason not to forge ahead.