In the Observer Tech Monthly climate change special, people were asked: “Which of the following should take the most responsibility for tackling global warming?” Surely, both the 45% who answered “governments” and the 13% who answered “households/individuals” are simply wrong. Only international agencies, including the UN, EU, G7, G20, IMF and the World Bank can take action at appropriate levels. We, including governments, should try to ensure that these institutions use power in the interests of the many and the environment, not the few, rich, individuals and corporations.

Many households and individuals already try to reduce personal carbon footprints, and this will continue. Worldwide, though, those who can’t afford to run a car, cook food or heat their homes adequately contribute more to reducing humanity’s collective footprint. Through the renewables levy in electricity bills, even those in fuel poverty contribute to the profits of multinational energy companies, whether or not those produce clean energy.

A recession helps lower emissions, yet governments still seek and applaud growth, however achieved. Governments cannot also act together to take the truly radical steps needed.

Jan Dubé

Peebles

I was amazed to see that we have an influential paper noticeably missing out any reference to population in the climate change equation. Our growing population drives consumerism. Meanwhile, the population of the world continues to creep up. In the UK, an estimated 1,000 births daily; worldwide, an estimated 10,000 births an hour. World population is projected to be eight billion by 2025, and that is a conservative estimate. Family planning is the most cost-effective way to reduce carbon emissions. £4 spent on contraception equals 1 tonne of carbon saved, as opposed to £35 spent on solar energy, for example. We can practice all the accepted methods to reduce carbon emissions, but a growing population will counteract all our efforts.

Our world population is responsible for increasing environmental degradation and is hastening CO2 emissions, the results of which will lead to runaway climate change, increasing poverty and famine.

Sheena Howarth

Worcester

I am really puzzled as to how you can run a major feature on climate change without a single reference to population growth. Agriculture is one of the biggest users of fossil fuel, and the necessity of feeding an ever-growing population means greater dependency on oil: it also means that more and more forests will be cleared, since we are already using practically all of the easily cultivable ground on the planet. The erosion of topsoil, rising sea levels, drought and more extreme weather all show how population levels and climate impinge on one another.

Are we afraid to discuss this? I’m more afraid of the consequences of not discussing it. Paul Ehrlich quotes one demographer as saying: “We will never reach a population of 10 billion: either because we do something about it, or because we don’t.”

Roger Plenty

Stroud, Gloucs

The nuclear industry must be patting itself on its radioactive back in response to your Tech Monthly chart, purporting to show that 91% of us would “prefer” to use energy “from less carbon-intensive sources (eg wind, hydroelectric, solar, nuclear)”.

These four energy sources, bracketed together by your innocuous-looking parentheses, are presented as environmentally equivalent. How quickly have we forgotten Sellafield, Chernobyl, Fukushima?

The undeniably urgent imperative to reduce carbon emissions should not blind us to the ever-present potential for catastrophe from nuclear power plant malfunctions.

Your chart takes for granted what needs to be questioned and debated: namely, can we “solve” the carbon crisis at the cost of 24,000 years of pollution (the half-life of plutonium 239)?

Benny Ross

Newcastle upon Tyne