How Could Rising Temperatures Affect Your City?

A decade ago, scientists believed that unchecked global warming could heat the world to 1.5 degrees C (2.7 degrees F) above preindustrial levels sometime around 2045. It now looks like we could pass this critical threshold as soon as 2030. Indeed, some research points to up to 3 degrees C (5.4 degrees F) of warming by 2050.

The difference in numbers here may sound small, but the implications are huge. Every fraction of a degree of warming above 1.5 degrees C will bring new weather extremes to many places — heat waves, fires, floods and more — alongside devastating impacts on lives and livelihoods.

While climate treaties and their negotiators trade in the language of degrees, it can be hard to relate global temperatures to what people are likely to experience in a particular locale — or how governments can prepare for these impacts.

To help fill in the picture, we analyzed dozens of climate models to discover how 1.5 and 3 degrees C of global warming might affect approximately 1,000 of the world’s largest cities. We focused on a few key impacts that many cities will face as temperatures rise:

• Extreme heat directly impacts health, productivity and economies, and is especially severe in cities due to urban heat island effect. We looked at the average number of heat waves cities could experience per year, as well as the average duration of each year’s longest heat wave.
• Energy demand for cooling has implications for power grids, electricity costs and greenhouse gas emissions. We looked at the number of cooling degree-days cities could face at each temperature threshold.
• Disease risk; specifically, how many days per year cities could experience temperatures conducive to the spread of insect-borne diseases, including arboviruses and malaria.

So, what do the models show where you live?