The biggest contributors to climate change are greenhouse gas emissions, primarily carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), which trap heat in the Earth's atmosphere, leading to global warming. The levels of these gases is now higher than ever before in human history (800,000 years) is because we burn fossil fuels like coal, have cleared forests, and from farming.  All these things have helped make our lives more comfortable – but we have done too much and now need to reduce our impact on the planet if we want to reduce climate change. 

The burning of fossil fuels for energy production, including coal, oil, and natural gas, is a major contributor to CO₂ emissions. To reduce this, we can transition to cleaner energy sources - often called renewable energy (solar, wind, and hydro).

Clearing of forests (deforestation) for agriculture and development contributes to both CO₂ emissions and reduced carbon uptake as part of photosynthesis. We can combat this by protecting forests, implementing sustainable land use practices, and reforestation.

Agricultural activities release methane and nitrous oxide, mainly from livestock digestion and manure management. More sustainable agriculture practices, such as reducing meat consumption, improving livestock management, and using low-emission fertilizers, can help.

The transportation sector is a significant source of CO2 emissions. Transitioning to electric vehicles, improving fuel efficiency, and investing in public transportation can reduce emissions. Landfills emit methane due to the decomposition of organic waste. Reducing waste through recycling and composting and capturing methane from landfills can help reduce emissions.

Stopping climate change requires a multi-faceted approach that combines policy changes, technological advances, and individual efforts. The best alternatives depend on the specific sector and the region, but a combination of renewable energy, energy efficiency, sustainable land use, and responsible waste management are key components of climate change mitigation.

Yes. The continent of Antarctica is covered by a giant ice block up to four kilometres thick. Most of the rock is below sea level, so if you took away all the ice, Antarctica would have a very different shape. Millions of years ago lots of plants and animals lived on Antarctica, and perhaps in the future they will again. But, it takes a long time to melt that much ice, so it's unlikely that any of us will ever see it.

Great question, lots of people want to be able to anticipate and prepare for natural disasters. Natural disasters vary in how they happen and how scientists can anticipate them, and we know more about some than we do about others.

For example, floods and bushfires are weather events. Scientists can provide very reliable forecasts of weather, particularly rainfall, which can give us advance warning of floods. These weather forecasts can provide accurate information for 1-7 days in advance, but predicting weather becomes more difficult the further away it is in time.  If we want to anticipate potential heavy rainfall and resulting floods further away in time, we can look at data from Australia’s Bureau of Meteorology (BoM). The BoM works to provide forecasts of rainfall and riverflow up to three months in advance. These seasonal forecasts can help state managers and the community anticipate times with increased chance of rainfall and flooding – and allow them to prepare. These kinds of predictions are in the timescale of days to weeks.

In contrast, earthquakes are not weather or climate events. To date, no one has ever successfully predicted an earthquake occurring. But scientists can calculate how likely it is that an earthquake of a certain magnitude will occur within a region over a certain number of years. Scientists make these calculations mostly based on the history of seismic activity (earthquakes happening) in a particular area, and work to anticipate how likely it is an earthquake will occur and what magnitude (size or strength) it will be. These kinds of predictions are in the timescale of years.

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.

This is a thought-provoking question. I would say the time to save our homes is NOW.

Regarding how much time we have, scientists cannot say with confidence how much time we have left to save our Earth. Because different scenarios depend on factors like how much greenhouse gas we are emitting and continue to be emitting, how the natural world is responding to the changes in climate, what are we doing to control our emissions etc. But scientists say that if we don’t want to suffer from extreme weather events, we should limit global warming to 1.5°C above pre-industrial levels by 2030. It is good thing that world leaders gathered in Paris, back in December 2015, and decided that all countries should aim to limit global warming well below 2°C and if possible 1.5°C - the Paris Agreement. Now, our job is to ask our countries' leaders what they are doing to keep their promise and achieve this goal and help them to achieve it by following their guidelines.

Regarding the melting of ice caps, it is important to keep in mind that it is one of the downsides of global warming but not the only contributor to global warming. The melting of ice caps can also increase the warming further by reducing Earth capacity to send back some of the energy coming from Sun into the space – scientists called this albedo effect (reflectivity of the Earth’s surface).

You would be happy to know that the scientists who studies sea level changes in past – paleo climate change, says that the Antarctic ice cap has survived much warmer times than current warming and it covers an area of about 14 million square kilometers, which is almost twice the size of Australia, and with an average thickness of about 2 kilometers. This is a huge amount of ice alone in Antarctica. So, it will take more than 81 years to completely melt all the ice caps in the world.

BUT the real concern is that ice caps in Antarctica and Greenland are melting at a much faster rate than they were in 1990s. And we are starting to see some extreme events, as you probably know, currently sea ice around Antarctica is not freezing as it should this winter. This kind of event is likely to happen if we don’t do anything now.

On average, the global sea level is expected to rise by about 40 cm, nearly half a meter, by 2050. Of course, sea level rise depends on how much carbon dioxide emissions are released by humans. However, in 2050 there actually isn’t much difference between predictions of the best (RCP2.6) and worst (RCP8.5) case scenarios. It is not until after 2050 that their paths really diverge. That’s because it takes a lot longer for the ocean and ice on the planet to respond than the atmosphere.  

Interestingly, the amount sea level rise will be quite different depending on where you are.  In Sydney, for example we might expect .2 m by 2050, but in NYC it could be up to .45. This is because there is a lot more land in the northern hemisphere and all that land is very heavy. Its weight actually pulls water to the north via the force of gravity. 

To calculate how much land that increase in sea level will flood, you also need to consider how far above sea level the coast line is. Over all, once you consider the shape the coastline around the world, we could be looking at 4.3 million acres underwater. That land contains the homes of 40-150 million people.