The warming arctic also weakens the jet stream to the extent that winter polar air can penetrate to middle latitudes, bringing brutal winter cold, sometimes for weeks.  In summer the same jet stream can stall in one position, allowing heat to build without respite to deadly temperatures, particularly in cities. Warmer summers draw more moisture from the ground, exacerbating droughts in some areas and feeding storm clouds in others, which can release torrential rains, eroding soil and flooding valleys.  The heat also warms the ocean, supercharging summer cyclones to the highest wind speeds ever recorded. And carbon dioxide absorbed by the oceans acidifies the water, threatening corals, shellfish and some plankton at the foundation of the marine food chain.

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The annual cycle also offers opportunities for renewable energy in concert with the seasons.  Solar energy peaks with the summer solstice, just as the weather gets hot and air conditioners turn on.  In winter the wind kicks up across the northern latitudes stirred by temperature differences.  Agricultural techniques such as permaculture and agroforestry, which shift from annual planting to perennial species, shade and protect the soil, allowing it to hold moisture and absorb rainwater, mitigating both drought and flooding.