When organic waste decomposes, carbon dioxide and methane gas is created. Methane is created when there is no air present, while carbon dioxide is the natural product when anything rots in air. So, basically – methane is produced when food goes to landfill, and carbon dioxide is produced when food is composted. As you probably know, carbon dioxide and methane are both greenhouse gases that are responsible for climate change. But methane is more than 25 times as potent as carbon dioxide at trapping heat in the atmosphere. So composting is better than sending food waste to the tip, but a better solution is for us to minimise food waste wherever we can.

The production and disposal of other types of waste also produces greenhouse gases, because these processes use natural resources such as water and fuel. Plastic waste produces greenhouse gas emissions during every stage of its lifecycle. The production and transport of plastic is dependent on oil, gas, and coal and so releases carbon dioxide into the atmosphere. In fact, waste management in general – including transportation, incineration, and other processing – is a huge contributor to greenhouse gas emissions. 

The shape of the Earth does influence the Earth’s climate. The curved surface of the Earth creates different climates across the globe.

The Earth has its shape because of gravity. As you might know, the Earth isn’t quite shaped like a perfect ball or sphere – it bulges out a bit around the middle, and the reason for the bulge is because the Earth is spinning.

Because of the Earth’s round shape, the equator is the closest point to the sun. It receives most of the sun’s energy and the polar regions receive less. This creates the warm tropical regions and cold polar regions. The extra heat at the equator also drives the movement of air up and away from the equator which creates the circulation patterns that form weather systems.

Gravity is also the reason why the Earth has an atmosphere – and as I’m sure you know, it’s actually the atmosphere that is responsible for climate change, because it contains greenhouse gases that trap heat.

Given our current laws of physics, no other shaped planet can naturally exist. If in another universe these laws are different, a planet would still need an atmosphere and still be susceptible to climate change.

The reason greenhouse gases stay in the atmosphere is gravity. Earth's gravity is strong enough to hold onto its atmosphere and keep it from drifting into space. And while there's some (very slow) escape of gas, that depends on how heavy a particular gas is. So while hydrogen & helium escape relatively easy, the main greenhouse gas, carbon dioxide, is relatively heavy and so it stays in the atmosphere.

Carbon dioxide can persist in the atmosphere for thousands of years. However other greenhouse gases like methane are gradually removed from the atmosphere by chemical reactions over a period of about 12 years.

Greenhouse gases are in the layer of the layer of the atmosphere that is closest to the surface of the earth (it’s called the troposphere). Gases get mixed around in the troposphere through a process called diffusion, which means they can be absorbed by plants growing on the Earth’s surface or in the ocean. Absorption by plants and also diffusion of carbon dioxide into and out of the ocean means that it’s not always the SAME carbon dioxide that’s in the atmosphere, even though the total levels are increasing because of emissions resulting from human activities.

It’s interesting to note that carbon dioxide is not evenly distributed over the globe; it is patchy with higher concentrations in some places and lower concentrations in others. This is because large-scale weather systems and patterns of circulation in the atmosphere influence the way that gas gets moved about in the troposphere.

One of the many fascinating and wonderful things about our planet Earth is that its climate is always changing. For literally billions of years, life on Earth has been influencing the planet’s changing climate. In fact, ancient microbes caused Earth’s first ever global warming.  The earliest photosynthetic microorganisms belched out enough methane to warm the planet by 15°C. This bout of global warming may have saved Earth from freezing over and created a comfortable climate for early organisms. Other climatic changes in the Earth’s history have been triggered by the changing configuration of continents and oceans, changes in the Sun’s intensity, variations in the orbit of Earth, and volcanic eruptions.

Climate change resulting from recent and current human activities is happening much faster than it ever has before, which means that many species (including humans) are struggling to adapt to the impacts of climate change. If humanity can meet its targets for reducing greenhouse gas emissions then we can slow and even reverse the current warming trend.

So while the Earth’s climate has always been changing over very long timescales – such as glacial and inter-glacial periods – and it will continue to do so, humanity does have the power to fix the current warming trend through global action to reduce greenhouse gas emissions.

This is a great question! Interestingly, during the peak of the COVID pandemic when a lot of people were in lock-down or choosing to stay home, we did see a small dip in pollution and also a very, very slight change in the rate of warming. This was partly because there was a lot less travel by road and air, and so lower emissions of the greenhouse gases, particularly carbon dioxide. The COVID pandemic was a good example of how our actions locally can make some difference to climate change

On longer timescales than the COVID pandemic, there are two main ways that we can link pollution to global temperature change. The first is by using evidence from the past. For instance, ice cores from Antarctica and Greenland contain information about past temperature, and about many other aspects of the environment. This is because the ice encloses small bubbles of air that contain a sample of the atmosphere – from these it is possible to directly measure the past concentration of atmospheric gases, including the major greenhouse gases: carbon dioxide, methane and nitrous oxide. Records from ice cores and other sources show a close connection between carbon dioxide levels and global temperature. Importantly, there are no examples in the ice core record of a major increase in carbon dioxide that was not accompanied by an increase in temperature. 

Global climate models are one of the main tools that scientists use to help understand how reducing pollution into the future might help reverse the increases in global temperature that we have seen over recent decades. Using these models, scientists can explore different scenarios (or future pathways) for reducing greenhouse gas emissions and understand how this will affect global temperature over the next 30 to 100 years. These models indicate that by reducing atmospheric pollution we can slow the rate of temperature increase and eventually reverse it.

Climate change is already affecting ecosystems in our oceans and on land, all around the world. In many cases these effects are negative ones, such as the impact of ocean warming and acidification on coral reefs, or the effects of changing ocean temperatures on the loss of giant kelp forests off the east coast of Tasmania. Loss of key species like kelp, or groups of species like corals, can have flow-on effects to many other species that depend on them for habitat or food, and so can quite quickly cause ecosystems to change completely.  

However, not all species or ecosystems are negatively affected by climate change. There are some winners as well as losers. One of the most noticeable ecological effects of climate change that we are seeing in the oceans and on land is large-scale movement of species as their habitats warm and they move (if they can) to follow the location of their preferred habitat. But of course not all species can move. Some might have limits to how far they can move (for example up a mountain), or they may not be able to move fast enough to keep up with warming temperatures. 

There are lots of things that we can do to help species and ecosystems adapt to the effects of climate change. Because the Earth’s climate is changing so quickly we may need to help some species by speeding up their rate of evolution. We can reduce the number of other human impacts – like pollution or fishing – so that species and ecosystems are less vulnerable to the effects of climate change. We may be able to use technological interventions to help some species or ecosystems adapt, such as relocating them or providing them with artificial substrates.