Renewable energy sources aren’t enough to eliminate the harmful effects of climate change, Bill Gates wrotein a recent blog post.

To prevent climate-related disasters such as floods, drought, and extreme temperatures, the world must focus on five “grand challenges,” Gates said.

While electricity is the largest single source of global emissions, sectors such as agriculture, manufacturing, transportation, and buildings also pose a threat to environmental safety.

Bill Gates has a message for those worried about climate-related disasters like hurricanes, droughts, flooding, and extreme temperatures: No solution works on its own.

In a recent blog post, Gates refuted the idea that renewable energy sources like solar panels and wind turbines hold the key to saving our planet.

“To stop the planet from getting substantially warmer,” he wrote, “we need breakthroughs in how we make things, grow food, and move people and goods – not just how we power our homes and cars.”

That’s a lofty goal – especially in light of a recent report from the Intergovernmental Panel on Climate Change (IPCC), which found that the effects of climate change could reach catastrophic levels in just two decades.

To get ahead of the problem, Gates said, the world must focus on five “grand challenges” to reducing greenhouse gas emissions, which linked to rising global temperatures. These challenges have also been identified by the Environmental Protection Agency as the main sources of global emissions.

Electricity

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Electricity is the largest single source of the world’s greenhouse gas emissions, producing about a quarter of the global total. But 75% of greenhouse gas emissions hail from other sources.

With global carbon emissions having increased by around 90% since 1970, the world cannot place its confidence in renewable sources alone.

Agriculture

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Between farming and deforestation, agriculture is responsible for around 24% of greenhouse gas emissions.

The main offender from this category is cattle, which produce more carbon dioxide emissions than most single countries, save for China and the United States.

But other elements of farming that can be dangerous as well. The use of nitrogen fertilizer, for instance, releases nitrous oxide, a greenhouse gas that’s 300 times more potent than carbon dioxide. In October, Gates and a cohort of billionaires invested millions in a genetically modified bacteria that could mitigate this problem.

Manufacturing

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The manufacturing industry is close behind in terms of emissions, producing around 21% of the global total.

When fossil fuels are burned to create things like steel or cement, they release harmful levels of carbon dioxide into the atmosphere. In recent years, scientists have also discovered that plastics release greenhouse gases as they break down in the ocean.

“Look at the plastic, steel, and cement around you,” Gates wrote. “All of it contributed to climate change.”

Transportation

Foto: sourceAirbus

The fourth challenge, transportation, contributes another 14% to global emissions.

While plenty of attention has been given to low-emission cars, burning fossil fuels for other forms of transportation such as airplanes, trucks, and cargo ships has even more damaging effects.

The shipping industry alone produces about as much greenhouse gas as Germany and Britain, and is expected to account for 17% of all emissions by 2050.

Buildings

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While buildings represent just 6% of global emissions, this number is likely to skyrocket as more people move to cities and demand additional building stock.

Within buildings, everyday fixtures such as heaters and lights soak up significant amounts of energy, while appliances like refrigerators and air conditioners release a potent form of greenhouse gas known as HFCs. To tackle these challenges, Gates recommends installing more energy-efficient windows and insulation systems.

Though small on their own, these elements represent a powerful collective threat to environmental safety.