Here's a simple explanation that I've read previously - Greenhouse gases in the atmosphere (methane, carbon dioxide, etc.) let visible light pass through, but absorb infrared light This causes the earth to heat up. The warmer atmosphere emits more infrared light, which tends to be re-absorbed Since the industrial age began around 1750, atmospheric carbon dioxide has increased by 40% and methane has increased by 150%. Such increases cause extra infrared light absorption, further heating Earth above its typical temperature range (even as energy from the sun stays basically the same). Energy that gets to Earth has an even harder time leaving it causing Earth’s average temperature to increase–– producing global climate change. Emissions are measurable. Temperature changes are measurable. The effects are measurable. They lead to the same conclusion. 97% of scientists agree. The standouts have ties to fossil fuel industries.
I understand & accept the science on all of that, but then how do we explain the multiple significant climate change events before industrialisation? The planet cooling & warming isn’t a recent event it has been occurring for millions if not billions of years
Nature holds all the trump cards to make humans extinct. Scorching temperatures that create huge drought and famine, to moonson rains that wash away arable land in an instance. Some experts think humans have less than a millennium left. Others less than that! I wonder if Hills/Corals/Betfred etc. will be opening a book on the likely extinction date? Not that anyone will be able to collect their winnings.
Not at all, but from what I've seen, scientists appear to be continually surprised at the speed at which these events are evolving. We must surely be accelerating the process.
How can they say that? We have zero data before 300 years ago. Certainly not enough to see where this current warming up fits into the longer term trend We have no way of under standing the “speed” of these climate events. But we do know the planet has been warming & cooling for millions of years
You are correct, there are natural cycles that affect the temperature of the planet. However, we've never seen such a swing in temperature over such a short timescale. The Milankovitch Cycle for example effects temperature changes over thousands of years, not a couple of centuries. https://en.wikipedia.org/wiki/Milankovitch_cycles
Fair enough. But can it be time stamped accurately enough to determine acceleration of a natural occurrence?
Absolutely. Layers are formed on the Earth's surface in very predictable ways. It's not just a few samples taken from one spot, it's thousands upon thousands of samples collected over decades on a global scale. I'm not sure how this image will show up on here, but this timeline effectively demonstrates average temperatures since the last ice age. Edit: Oh my God, it's massive!
And even on that, there isn't a consensus on how it is interpreted, especially at the points the differing techniques are 'joined' on a graph. There are even debates on how to correct the data collected from the monitoring sites, as many use different equipment, others have changed locations, and others have had the area around them changed in a way that can effect readings, and yet more was based on modeled predictions where the validation process is subject to even more debate. It's just one of many reasons why anyone citing the 'consensus' is rarely if ever someone that understands the scientific process, never mind the questions. You can't offer a solution, if you're not clear on what the problem is. None of which makes me a denier, it just means that I tend to look quite deeply in to the background of some media soundbites. Just have a look in to many of those sponsoring COP's. Have a look at the reality of some of the 'solutions' that people on here would like to call 'green'. Have a look at some of the earlier claims by the same experts, that are now checkable. Have a look at the actual impact some of the proposed changes will have on the developing world, as well as global economics. Focusing on reducing emissions is absolutely the way forwards, as is accepting the need to use finite resources sparingly but it also need be investment in adapting homes and lifestyles to changes in our environment, as they are liable to arrive irrespective of what we do.
Of course temperature readings from stations situated in places where local environs have altered have been adjusted, that's how you standardise the data. In fact, I think there's a documentary on iplayer about it. Yeah, Climategate. Not that I've seen it but obviously I know what it's about. Personally it's of no concern to me what the media says about it. I have no care for Greta. I'm interested in the science. I want to know the process behind the results and what processes aid those. I didn't believe humans could have such a global effect but I hadn't realised how much went into these predictions and for how long. Standing on the shoulders of giants and all that. The solution is to collectively reduce our CO2 output. It will be painful for a lot of people, but not as painful as inaction. I also don't believe that our individual actions can reverse what has happened. Big businesses and industries are who got us into this, they are the ones who should get us out.
The documentary you mention contains a fair number of errors. Many of the measures to control the climate focus on CO2 (and often erroneously 'carbon') but many of the measures offered to remedy it, actually increase other gasses that have a greater global warming potential.