AS Level Climate Change?! Watch

(Original post by MrHarry)
Just a quick query... I don't quite understand why climates are shifting? Like, why is the Arctic tundra region shifting North (and where North?!) and why is our climate (UK) going to be changing due to the French/Spanish climate moving up towards us?

An idea that's baffling me. Not many things do, but this...

(Original post by Chlorophile)
That's an extremely complex question. Very, very broadly, it's because the earth is warming (I'm guessing you're familiar with the greenhouse effect). Tundra environments exist in a band where the temperature (and other conditions) allow them to exist. Because they can only exist in very cold environments, the tundra is limited to high latitudes. If you warm the earth, the parts of the tundra that were already the warmest (i.e. closest to the equator) can warm to the point where they're no longer cold enough to support the tundra. Parts of the tundra that are at higher latitudes (and therefore colder) will still be cold enough to support the tundra with warming. So the net effect is that the tundra boundary moves north (or south in the case of the southern hemisphere). The tundra itself isn't moving because there isn't anywhere for it to move to since they already occupy the highest latitudes (they're limited by ice sheets which could in theory melt and in the case of Antarctica, allow the tundra to expand further south but I don't think you need to worry about that). The thing that's moving is the boundary of the tundra in response to changing environmental conditions.

It's a similar thing for the UK although it's probably not entirely accurate to say that we're going to get the climate of Spain. In general though, you've got a general warming trend which means hot places are getting hotter and cold places are getting much hotter (since cold places are disproportionately affected). But there are many other factors other than temperature which, if you want to get into higher levels of complexity, you have to consider. Does this help?

(Original post by MrHarry)
Very much so, especially the top point. I can't believe I was missing that! However, I do recall my teacher saying about how biomes will be shifting and we will be living in a different biome in the distant future, subsequently so will regions like Spain. Have I misinterpreted this?

Also I appreciate you posting - and apologise for being so broad, climate change is my weakest point!

(Original post by Chlorophile)
The climate is a really complicated thing. Whilst it's true that temperatures are generally rising, it's very difficult to make precise statements like "Britain will be like Spain in the future". Biomes definitely are shifting and the future will definitely be very different from today, but it's not just as simple as saying "The world will be X degrees warmer in Y years time so area Z will look like this then". There are lots of other factors. For instance, if - and god help us if this happens - warming became severe enough to cause a flood of meltwater to enter the north atlantic, what's called the "thermohaline circulation" could shut down. Why this would happen is a bit complex but long story short, it would cause Britain to have a climate similar to that experienced by Moscow at the moment. So you need to consider more things that just temperature!

(Original post by MrHarry)
Ah, I see. That's actually really interesting, I've just been reading up on it. I'm doing revision at the moment at home (half term) so I can't ask my teacher to clarify this next bit, I was wondering if you or somebody else could... I understand the concept of temporal patterns and glacial periods, although what I don't understand is:

a) Why do Elliptical Orbits bring about cooler temperatures initially? I understand the concept of -0.5oC and thus evoking the albedo effect - but why the decrease in the first place? Is it due to the latitude from the equator increasing?

b) I wrote this in my notes a while ago when I was ill and not really paying much attention, could you perhaps clarify/correct it?:
"The gravitational pull of other planets on planet Earth stretch out the Earth even more in elliptical periods - this makes a circular orbit".

I don't think that sounds right - does it?

Thanks for all your help so far, you're a life saver.