The climate changes because it is forced to do so. That may sound a little strange, but 'forcing' is a real technical term for any pressure that causes the 'average weather' to shift. Positive forcings (e.g. increased solar activity, more greenhouse gases) induce global warming, whereas negative forcings (e.g. more low-level clouds, volcanic dimming) result in cooling. Climate system feedbacks (e.g. melting ice, more water vapour) act to enhance these processes. That's the way it's always been, throughout Earth's long history. When the planet is thrown out of energy balance by a change in forcing, it must respond, by warming or cooling. It can't be bargained with and it has no room to compromise. It will do what it must do. It's the laws of physics.
So there's no point in half-fixing climate change. If this is our strategy, whether implicit or explicit, people may as well enjoy the Platinum Age (as Ross Garnaut calls the last few decades) and be done. Cap-and-trade systems to reduce emissions by some percentage are a good example of an ultimately useless 'half-fix' policy. Due to the long lifetime of carbon dioxide (CO2) in the atmosphere (about 20 per cent of CO2 released today will still be airborne in 1000 years), it is only the total amount of CO2 released by humanity during the fossil-fuel age that really matters. We must limit total emissions.
In order to stop forcing the climate system towards further warming - to avoid the worst predicted impacts of climate change - we therefore have to stop using coal, oil and gas. We cannot afford to burn all of the available reserves of these, and other carbon sources, such as tar sands and oil shales.
But modern society needs energy. Lots of it. Although there is plenty of scope for more efficient use of energy in developed nations, the developing world is desperately striving for energy growth. The obvious source of energy for these emerging economies is the same source used by the developing world to build its wealth and prosperity. Wishing this weren't so won't make that fact go away.
But if neither the developed or developing worlds can risk using coal, oil and gas, where does this energy come from? Renewable energy, for instance solar, wind and wave power, is clean, and there are huge amounts of it available. But it is diffuse - vast areas of land or coastline must be harnessed to use it on a significant scale - and it is mostly intermittent, so a distributed grid with plenty of storage and backup is essential. Scaling up renewables to be a viable replacement power source on a planetary scale is an incredible logistical challenge, and quite possibly not ever achievable.
This above should not be taken to imply that I do not support expansion of renewable energy and widespread adoption of energy efficiency measures. In some places there are wonderful opportunities for these. For instance, Australia could cut its greenhouse emissions by around 30 per cent, at no net cost, due to the payback from lower power bills thanks to more sensible use of energy. Further, Australia has a wealth of renewable energy options at its disposal (huge deserts that are perfect for solar thermal power, long stretches of windy coastline for large turbines, and a large endowment of deep hot dry rocks that have the potential to supply baseload geothermal energy).
Sadly, that isn't the case everywhere. Some nations with large populations have few renewable energy sources available to them. And even for Australia, it will almost certainly be too difficult and costly to run our entire energy economy using renewable power, without sufficient non-coal backup.
Nuclear energy may well be that backup, or indeed a mainstay for future energy generation. For instance, there is a technology developed at the Argonne National Laboratory USA called integral fast reactor nuclear power, which burns up 99 per cent of the nuclear fuel, leaves no long-lived waste, is passively safe ('meltdowns' are exceedingly unlikely) and does not generate weapons-grade material (see Integral Fast Reactor [IFR] nuclear power - Q and A, for more details). It's been researched for over 10 years and is ready for demonstration. It warrants further attention.
One risks ire from many sides when discussing nuclear energy as a climate solution. Those climate sceptics with a vested interest in the fossil fuel forever status quo will say there is no climate or energy supply problem to fix, so why bother? Hardened environmentalists will tell you that nuclear in any form is unsafe, polluting, risks weapons proliferation, and is unnecessary given renewable power sources (even when briefed about how integral fast reactors solve all of these concerns). No matter. It is vitally important that everyone else, and that's most people, understand the real issues.
So my basic point is this. Do you wish to fully solve the climate crisis? Or alternatively, do you want a secure energy supply that is not dependent on foreign oil and other dwindling, polluting sources? If you are merely satisfied with half-fixing these problems, then sure, hold your ideological ground.
But if you're honest about seeking real solutions, it's time to lay out all of the future-of-energy cards on the table, for open and rational discussion. Nuclear may well be the ace in the deck, or it may be the card that makes up the royal flush. Either way, don't throw it on the discard pile.