As the largest carbon emission contributors, urban areas should be capable of tackling climate change without government support.

But convincing people to abandon their cars and rapid urbanisation in the developing world are significant obstacles.

Since US president Donald Trump decided to remove the US — the world’s second largest polluter — from the Paris Accord, mayors of over 7,400 cities in the US and around the world have pledged to meet climate targets, in spite of his decision.

This is unsurprising; cities stand to suffer the most from climate change.

The urban heat island effect makes cities up to 7.8 degrees Celsius warmer than their surrounding rural areas and many are located on major rivers or in coastal areas which make them vulnerable to rising sea levels.

Consuming two-thirds of the world’s energy and generating around 70 percent of global carbon emissions, cities should — in theory — be able to fight climate change almost entirely on their own.

Urban mayors are currently acting as the driving force in the fight against climate change and many European cities are already on course to achieve their target of reducing emissions by 20 percent from 1990 levels by 2020.

But, cities across the world share a common problem, cars are major polluters and people are not yet willing to abandon their private vehicles entirely.

In European cities, emissions from the transport sector have only reduced by seven percent between 1990 and 2016.

A report from the LSE found that 35 percent of Londoners still use a car as their most common mode of transport for daily travel, and the majority of Londoners still cite their car as their most preferred method of transportation.

This would not be an issue if electric (zero-emission) cars were used for these journeys, but these vehicles are yet to hit the mass market; in June 2017 just 1.8 percent of new car registrations in the UK were electric.

Public transport is already the cheapest and most efficient mode of transport in many cities, but mayors need to go beyond this by making public transport the favourable way to commute — a major challenge.

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Additionally, the developing world is currently experiencing rapid rates of urbanisation; this in itself creates a problem.

As urban economies grow in size, pollution from factors such as traffic and power generation will rise in correlation.

Ensuring urbanisation is sustainable and environmentally friendly requires substantial governmental planning and financial resources, which are commonly unavailable in the developing world.

Additionally, the metals and concrete commonly used in infrastructure construction are carbon-intensive to manufacture, meaning fast urbanisation in the developing world will create significant amounts of additional greenhouse gas emissions.

Cities have proven they are willing to battle climate change, despite the lack of support from the leader of the free world. But, changing attitudes towards cars will prove the biggest challenge for urban mayors.

Also, as the developing world becomes increasingly urbanised, there is likely to be limited government planning to ensure growth creates as little environmental impact as possible.