It has been discovered that Humans now cause have caused the seasons. Right now in the northern hemisphere people are burning fossil fuels to stay warm. That in turn causes the atmosphere to heat up and soon they stop burning to keep warm. That creates summer where they burn less and allows the hemisphere to cool, creating winter again.
Now hemispheres are on opposite sides of the Earth. Therefore, the seasons are in opposition to each other. If everyone would stop burning to stay warm, the Earth would eventually level off and remain a constant tempature.
/S