Orbital forcing

Imagine you're on a really big merry-go-round that's spinning around and around. This is kind of like the Earth going around the sun, except the merry-go-round never stops spinning.

Now imagine that someone comes along and gives the merry-go-round a little push every once in a while. This makes the merry-go-round speed up or slow down, even though it's still spinning around the sun.

This is kind of like what happens with something called "orbital forcing". The Earth's orbit around the sun isn't a perfect circle - it's more like an oval shape. This means that sometimes the Earth is closer to the sun, and sometimes it's farther away.

When the Earth is closer to the sun, it gets more sunlight and it's warmer. When the Earth is farther away, it gets less sunlight and it's colder. This can cause things like ice ages or warm periods.

But there are also other things that can cause the Earth's orbit to change. For example, the gravitational pull of other planets can make the Earth's orbit more circular or more elongated. This can affect how much sunlight different parts of the Earth get at different times.

So all these little things - the shape of the Earth's orbit, the gravitational pull of other planets - can add up over time to affect how much sunlight the Earth gets and how warm or cold it is. And that's what we mean when we talk about "orbital forcing".