Correct Answer: Arctic sea ice, Carbon dioxide, Global temperature, Sea level, and Land ice

Solution : The correct answer is Arctic sea ice, Carbon dioxide, Global temperature, Sea level and Land ice.

All of these variables are changing at an unprecedented rate, and the evidence clearly shows that these changes are the results of human activities, for example, the use of fossil fuels. Since the pre-industrial period, the global surface temperature has risen by around one degree Celsius, and carbon dioxide levels in the Earth's atmosphere have increased by around 40%. The water level is rising at an alarming rate. The melting of Arctic sea ice is a terrifying prospect. The Arctic is warming twice as fast as the rest of the planet, causing sea ice to melt.