If global emissions are not significantly reduced, London will experience a 'radically different climate' by 2056. That is the message from a new study published by researchers at the University of Hawaii, who have calculated how global warming is likely to affect major cities around the world in the coming decades.
Camilo Mora and his team used multiple atmospheric projections to calculate the expected date by which different parts of the world are likely to experience a climate that differs from anything they have experienced in the past 150 years.
It shows that the first areas to be affected will be in the tropics - the city of Manokwari in Indonesia, with 286,000 people will be first to notice a departure from normal temperatures and levels of rainfall, in 2020.
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Jakarta, capital of Indonesia, and Lagos (Nigeria), home to 28m and 8m people respectively, will both undergo a climate shift by 2029.
The following decade will see Mexico City (2031), Mumbai (2034) and Bogota, Cairo, Nairobi and Baghdad (2036) follow suit, while the 2040s will affect New York, Rome, Tokyo, Beijing and San Francisco. London is expected to experience the change in 2056.
Last to be hit by the increases in temperature will be northern cities such as Moscow (2063), Reykjavik (2066) and Anchorage, Alaska (2071). According to Mora's predictions, the average location on the planet will have shifted climate by 2047 if current emissions trends continue unabated. You can browse a full list of world cities and the dates Mora's team predict for them here.
If we can curb emissions further - reducing carbon dioxide levels to approximately half (538parts per million by 2100 compared with 936ppm) - the average date for historically significant change moves to 2069.
Ryan Longman, one of the scientists behind the study, told Climate News Network that "Our results suggest that countries first impacted by unprecedented climates are the ones with the least capacity to respond. Ironically, these are countries that are least responsible for climate change in the first place."
The definition of historically significant change taken by the team refers to climate that goes beyond the maximum or minimum bounds of anything experienced between 1860 and 2005. City climates were chosen to highlight the effect that climate change could have on human populations, rather than the environment.
The report claims that climate change on this level could have wide implications for society, noting that consequences could include changes to "human welfare, through changes in the supply of food and water; human health, through wider spread of infectious diseases, through heat stress and through mental illness; the economy, through changes in goods and services; and national security as a result of population shifts, heightened competition for natural resources, violent conflict and geopolitical instability."
Later in the century, the report indicates that every consecutive month could set records for high temperatures; in an extreme scenario, tropical regions could experience this as soon as 2050.