[Note from moderator: This is a very long post and off topic. Further discussion of the subject must happen elsewhere. ] To the moderator - while this post is a bit off topic, I hope you can indulge me and post it, if only because it explains why I am no longer working on n-categories. The math is near the end. Dear Andre - You write:
You wrote that the situation about climate change is hopeless. I can understand your pessimism, but how do you really know?
First of all, climate change is already upon us. So far this year has been the hottest in recorded history, and we're seeing precisely the erratic precipitation patterns that we'd expect from global warming. Droughts and heat waves in Russia have caused that country - the 3rd largest grain exporting country - to ban exports of wheat. Floods displaced 2 million people in Pakistan, 2 million in Nigeria, and hundreds of thousands Uganda, Kenya and Sudan. We're also seeing unusual things like tornadoes in New York City, and coral reefs dying from overheated water in Indonesia. Etcetera. Second of all, once carbon dioxide is in the atmosphere, a large portion stays there for hundreds or thousands of years. So, to prevent the CO2 concentration from rising above 450 ppm, truly astounding actions would be required STARTING NOW. Let me quote Stewart Brand's summary of a talk by the engineer Saul Griffith:
What would it take to level off the carbon dioxide in the atmosphere at 450 parts per million (ppm)? That level supposedly would keep global warming just barely manageable at an increase of 2 degrees Celsius. There still would be massive loss of species, 100 million climate refugees, and other major stresses. The carbon dioxide level right now is 385 ppm, rising fast. Before industrialization it was 296 ppm. America's leading >climatologist, James Hansen, says we must lower the carbon dioxide level to 350 ppm if we want to keep the world we evolved in.
The world currently runs on about 16 terawatts (trillion watts) of energy, most of it burning fossil fuels. To level off at 450 ppm of carbon dioxide, we will have to reduce the fossil fuel burning to 3 >terawatts and produce all the rest with renewable energy, and we have to do it in 25 years or it's too late. Currently about half a terawatt comes from clean hydropower and one terawatt from clean >nuclear. That leaves 11.5 terawatts to generate from new clean sources.
That would mean the following. (Here I'm drawing on notes and extrapolations I've written up previously from discussion with Griffith):
"Two terawatts of photovoltaic would require installing 100 square meters of 15-percent-efficient solar cells every second, second after second, for the next 25 years. (That's about 1,200 square miles of solar cells a year, times 25 equals 30,000 square miles of photovoltaic cells.) Two terawatts of solar thermal? If it's 30 percent efficient all told, we'll need 50 square meters of highly >reflective mirrors every second. (Some 600 square miles a year, times 25.) Half a terawatt of biofuels? Something like one Olympic swimming pool of genetically engineered algae, installed every second. (About 15,250 square miles a year, times 25.) Two terawatts of wind? That's a 300-foot-diameter wind turbine every 5 minutes. (Install 105,000 turbines a year in good wind locations, times 25.) Two terawatts of geothermal? Build three 100-megawatt steam turbines every day — 1,095 a year, times 25. Three terawatts of new nuclear? That's a 3-reactor, 3-gigawatt plant every week — 52 a year, times 25".
[...]
Meanwhile for individuals, to stay at the world's energy budget at 16 terawatts, while many of the poorest in the world might raise their standard of living to 2,200 watts, everyone now above that level would have to drop down to it.
I believe actions of this scale will not happen in time, and thus it's hopeless to prevent a disaster. However, that does not mean we should give up! Even if a disaster of some sort is certain, there are different degrees of disaster, and it’s our responsibility to minimize the disaster.
You also wrote that not all human beings will die. Is this a source of optimism?
It is for me! I like people.
Who should be saved? Who can be abandoned?
Luckily for me, there are lots of useful things I can do without knowing the answer to this question.
You also wrote that we should consider using geo-engineering.
More precisely, I think we should study geo-engineering. People are already considering it, regardless of what I say. The pressure to use it will become intense as things get worse. Some forms, such as biochar, might be quite safe if managed properly. Others, which do not reduce the CO2 level, could be very dangerous. (People disagree on whether biochar counts as geo-engineering. It simply means turning agricultural waste into charcoal and burying it: http://www.azimuthproject.org/azimuth/show/Biochar)
How different is your position from Bjorn Lomborg's?
I haven't read Lomborg's new book yet, so I'm not sure. However, I get the feeling that he advocates geo-engineering as a cost-effective way to prevent global warming. My position would then be different. I believe we won't do anything significant about global warming until it's too late and there are massive social disruptions. Then there will be extreme pressure to try anything, including geo-engineering. So, I think it's important to study geo-engineering along with all other solutions. If people who don't like it refuse to study it, only people who like it will study it - so they'll be the ones that governments will consult. Now, about mathematics:
I hope you will not leave math. Everybody likes your web pages on maths and physics.
Thanks very much! I'm trying to figure out how to combine my interest in math with my desire to help save the planet. There are lots of options; the problem is finding one that achieves a significant effect. To do pure math, I just needed to follow the beauty. But this is different. There are easy things, and harder things. Everyone who teaches math can incorporate real-world examples in their teaching, and use them to educate people about the world we live in. For example: overfishing can cause fish populations to crash. This can be seen in a very simplified way using the equation dP/dt = kP - c or in more realistic ways using more complicated equations. A mathematician friend of mine was shocked when two colleagues of his, experts on differential equations, didn't know this. When I heard his story, I realized we should be talking about overfishing every time we teach kids how to solve separable differential equations. Another slightly more sophisticated example involves the role of feedback in global warming. I'm sure there are many more. I'll collect them and make them easy to find. More generally, everyone who teaches math or science can help students think clearly about real-world problems. This is urgent! Logic and statistics are vital. Mathematicians and scientists should also spend more of their research time on environmental issues. For students this should be easy: these issues will become ever more important, so working on them is a good road to a successful career - much easier than, say, category theory. Other people may feel they're too old to change directions. But in fact, I've found that the best way to become young is to try something new. Being tenured makes this very easy to do. The hardest part is figuring out which actions will have the optimal effect. For me, the first step is to quit pure math, work on environmental issues, and trying to convince large numbers of scientists to turn their attention in that direction. But the last part will only work if I can find a path forward that looks attractive. Best, jb [For admin and other information see: http://www.mta.ca/~cat-dist/ ]