Humans have caused climate change by pumping ever more carbon dioxide into the atmosphere and we must quickly cut these emissions.

True, but what has this got to do with unions?

Well, at their core unions are organizations that bring people together to fight for the common good. This essential truth is reflected in the structure, philosophy and history of most unions.

But exactly whose “common good” a union is fighting for can vary widely.

Is it narrowly defined as immediate job interests of local union members? Is it the common good of all those working in a particular trade? All union members in one industry?

Or is it more widely defined as the common good of every union member? Every worker in a particular country? Of all Canadians? All the workers of the world? Every person in the world? Or even wider as the common good of all life on the planet?

The truth is every thoughtful union member, and especially every union leader, must consider the common good from many different perspectives. Everyone has more than one self-interest and therefore more than one common good.

No one is solely a pipefitter, nurse, front desk clerk; or employee of General Motors; we are also children, parents, residents of a city or town, citizens of a country, inhabitants of a planet who are dependent on a common environment, and much more besides.

But unions often find it easiest to fight for the narrowest common good, the immediate self-interest of workers in a particular trade, industry, or company. Higher pay, improved benefits, better job security — members almost always cheer if a union achieves these things. Fighting for all life on the planet or against inequality is a bit more complicated.

But there is another reason as well why unions find it easiest to fight for the narrowest common good. “Looking after No. 1” is what capitalism tells people to do. You are a consumer. Buying more is what life is all about.

In fact, proponents of capitalism argue there is no such thing as the common good, that we are all simply individual consumers and therefore unions are an illegitimate intrusion into the free market. Still, if workers are going to unite for any purpose it had better be limited to stuff like higher pay, something that allows people to buy more and does not challenge capitalism.

So, here’s the reality we face: In so far as a union, its leadership and members have bought into capitalism, the greater the likelihood that union will choose to focus on a very narrow self-interest and ignore such issues as climate change or inequality. Some unions do buy into capitalism despite the fact it does not like workers joining together to fight for any common good, whether narrowly or broadly defined. If it were up to capitalists there would be no unions at all. Capitalists — the bosses — are not our friends. The more people buy into their system the weaker unions are.

And the opposite is also true. The more people come together to fight for the common good, the stronger unions are. The more unions fight for the widest common good, the more people will be on our side and the stronger unions will be. The more unions fight the existing system the stronger unions are.

History shows that the periods of greatest growth in unions were times when capitalism faced widespread challenges and the periods when unions have shrunk, like during the past 20 years, were times when opposition to capitalism was weak.

History also shows that unions have been willing to fight for the widest common good despite opposition from the rich and powerful. Unions were part of the struggle to end slavery and child labour; unions helped win universal voting rights, public education, equal rights, Old Age Pensions, Medicare, the 40-hour work week, paid vacations and numerous other social programs that have benefited society as a whole.

It won’t be easy to stop global warming. Many brothers and sisters earn their living extracting oil, building private automobiles and mining coal, industries that must shrink or disappear to save our planet. Of course this raises difficulties inside the labour movement because it pits narrow self-interest against the wider common good.

But progressive unions were not deterred by similar internal problems in the struggle for civil rights or against sexism and homophobia. As in those battles we must do what is necessary and right. We must demand jobs that do not harm the environment. We must not shy away from battling climate change because there is no more important common good than the health of our environment. We must learn from and work with environmentalists.

But environmental activists must also learn an important lesson from the long history of the labour movement: Capitalism is the problem and certainly not the solution.

The capitalist drive to maximize profits explains the externalizing of environmental costs. Capitalism is a system of small minorities profiting at the expense of others. Private ownership of what are social means of livelihood allows capitalists to make decisions that pass the real costs of industry to communities, workers, future generations and other species.

Capitalism requires growth. But what happens when the environment needs a smaller human footprint? When, at least in wealthier countries, we must learn to live with less stuff?

If a capitalist economy shrinks for a sustained period the system goes into a crisis. Banks crash, unemployment rises and wars suddenly make sense to rich people in order to get their system growing again.

Supporters of capitalism claim the system is based on freedom and choice, but when it comes to the environment for many people this amounts to the freedom to choose between destroying the planet or having a job. The promoters of tar sands, fracking, coal mining and pipelines are explicit about this. The business pages are full of stories quoting the captains of the carbon-industrial complex as telling us: “You must choose between economic prosperity and what is good for the environment, because you can’t have both.”

With capitalism they are correct.

Yet some environmentalists, as well as some union members, look to capitalism for solutions. That’s like expecting Toronto Mayor Rob Ford to tell the truth. A sustainable, democratic economy is incompatible with a system run in the interests of a tiny minority that constantly demands more profit.

Science leaves little reasonable doubt that the burning of currently known reserves of coal, oil and natural gas will push atmospheric carbon dioxide levels past a tipping point, after which rising global temperatures will irreversibly undermine the conditions on which human life as we know it depends.

Despite the evidence, today’s capitalism rests on the expansion of fossil fuel production and use.

In Canada, capitalist investment is focused on expanding tar sands production. The promoters claim that these developments will create jobs. But every analysis shows more jobs would be produced if equivalent investments were made in solar, wind and geothermal power. Far more jobs could be produced by investing in domestic employment for domestic markets, in the production and distribution of sustainable local agriculture, clothing, etc. Even more jobs would be created by investments in childcare, elder care, social housing, public transit and other green infrastructure.

More jobs but less profit. Capitalists invest in fossil fuels because corporate profits now largely depend on cheap fuel. Equivalent profits cannot be made meeting actual human needs.

So, unions and environmentalists share a common enemy: an economic system run by and for the wealthiest people in the world.

Together we can fight for a different sort of economic system that will prosper in harmony with the environment. Or apart we can fiddle with capitalism as our planet burns.