Africa is the most vulnerable to climate change

Africa accounts for less than 4% of the global total of carbon emissions, which cause global warming yet Africa will be hardest hit by climate change. Out of the world’s top 10 countries most vulnerable to climate change, seven are African countries - Sierra Leone, South Sudan, Nigeria, Chad, Ethiopia, the Central African Republic and Eritrea.

There are four key reasons for this:

• First, African society is very closely coupled with the climate system; hundreds of millions of people depend on rainfall to grow their food
• Second, the African climate system is controlled by an extremely complex mix of large-scale weather systems, many from distant parts of the planet and, in comparison with almost all other inhabited regions, is vastly understudied. It is therefore capable of all sorts of surprises
• Third, the degree of expected climate change is large. The two most extensive land-based end-of-century projected decreases in rainfall anywhere on the planet occur over Africa; one over North Africa and the other over southern Africa
• Finally, the capacity for adaptation to climate change is low; poverty equates to reduced choice at the individual level while governance generally fails to prioritise and act on climate change

African climate is replete with complexity and marvels. The Sahara is the world's largest desert with the deepest layer of intense heating anywhere on Earth. In June and July the most extensive and most intense dust storms found anywhere on the planet fill the air with fine particles that interfere with climate in ways we don't quite understand.

The region is almost completely devoid of weather measurements yet it is a key driver of the West African monsoon system, which brings three months of rain that interrupts the nine-month long dry season across the Sahel region, south of the desert. No other region has documented such a long and spatially extensive drought.  Evidence points to Western industrial aerosol pollution, which cooled parts of the global ocean, thereby altering the monsoon system, as a cause.

In southern Africa we are seeing a delay in the onset and a drying of early summer rains, which is predicted to worsen in forthcoming decades. Temperatures there are predicted to rise by five degrees or more, particularly in the parts of Namibia, Botswana and Zambia that are already intolerably hot.

Meanwhile over Kenya and Tanzania, the long rains from March to May start later and end sooner - leading to an overall decrease in rainfall. This observed change sits uncomfortably next to predictions of a wetter future in the same season - a problem scientists have termed the East African Climate Paradox.

Central Africa, one of three regions on the planet where thunderstorms drive the rest of the planet's tropical and sub-tropical weather systems, lives perilously close to the rainfall minimum needed to support the world's second largest rainforest system. Even a little less rainfall in the future could endanger the forest and its massive carbon store. We know remarkably little about that climate system - it is scarcely even monitored - there are more reporting rain gauges in Oxfordshire than the entire Congo Basin.

Africa's complex climate system is, unusually, influenced by all three global ocean basins. Emerging from one of those rapidly warming oceans, tropical cyclones Idai and Kenneth in March and April 2019 destroyed parts of Mozambique, Zimbabwe and Malawi, with Kenneth following a particularly unusual path over Tanzania.

Each region and sub-region of Africa is changing differently but an emerging commonality is a shift towards more intense rainfall - even where there is observed and projected future drying. The rainfall arrives in shorter bursts, causing more runoff and longer dry-spells in between. Central to that rainfall change is the behaviour of thunderstorms, which deliver around 70% of African rain.

Africa has a lot of coastal cities so as sea levels rise, these cities will be more prone to flooding