How might climate change alter global atmospheric circulation patterns?

• A. Hadley cells expand, jet streams shift, and more extreme weather in some regions with altered monsoon timing and intensity.
• B. There will be no significant changes to atmospheric circulation.
• C. Jet streams will disappear entirely and Hadley cells will contract.
• D. Global circulation will become uniform with less regional variation.

Answer: (A)

When the climate warms, the uneven heating that drives the atmosphere changes the strength and position of the big circulation cells. The tropics warm faster, which tends to push the Hadley circulation outward toward mid-latitudes. That shift moves the major rainfall belts and can alter monsoon timing and intensity in regions like Africa, Asia, and the Americas. At the same time, the upper-level temperature gradient changes, nudging the jet streams northward and making them more wavy in some areas, which changes where storms travel and how strongly they rain.

So you’d expect expansion of the Hadley cells, a poleward shift of the jet streams, and more extreme weather in some places along with altered monsoon behavior. The other ideas don’t fit what climate models project: circulation won’t stay the same, jets won’t disappear, and global circulation won’t become uniform.