The Intergovernmental Panel on Climate Change (IPCC) published data on the contribution of different economic sectors to global greenhouse gas emissions. Un...

(a) The sector that produces the most greenhouse gas emissions globally [1]

Energy (electricity and heat) at 25% of global greenhouse gas emissions. [1]

(b)(i) How rice paddy farming contributes to greenhouse gas emissions [2]

Rice paddies are flooded fields where waterlogged conditions create anaerobic (oxygen-free) environments in the soil. [1] Bacteria in the waterlogged soil decompose organic matter anaerobically, producing methane (CH₄), which is released into the atmosphere. Methane is a potent greenhouse gas with a much stronger warming effect per molecule than CO₂. [1]

(b)(ii) How cattle farming contributes to greenhouse gas emissions [2]

Cattle produce large amounts of methane through enteric fermentation, a digestive process in their stomachs where microorganisms break down cellulose, releasing CH₄ as a by-product. [1] Methane is a potent greenhouse gas, approximately 28 times more effective at trapping heat than CO₂ over a 100-year period, making cattle farming a significant contributor to global warming. [1]

(b)(iii) How deforestation for agriculture contributes to greenhouse gas emissions [2]

Deforestation removes trees that act as carbon sinks, absorbing CO₂ from the atmosphere during photosynthesis and storing carbon in their biomass. [1] When forests are cleared by burning, the carbon stored in the trees and soil is released as CO₂ into the atmosphere, contributing directly to increased greenhouse gas concentrations. [1]

(c) Two methods farmers could use to reduce greenhouse gas emissions [2]

1. Using precision farming techniques to apply the minimum amount of nitrogen fertiliser needed, reducing nitrous oxide (N₂O) emissions that result from excess fertiliser breaking down in the soil. [1]
2. Improving livestock feed and breeding to reduce methane production per animal, or using biogas digesters to capture methane from animal waste and convert it into usable energy, preventing its release into the atmosphere. [1]

(d) Two ways in which transport emissions could be reduced [2]

1. Transitioning from petrol/diesel vehicles to electric vehicles powered by renewable electricity, which eliminates exhaust-pipe CO₂ emissions during use. [1]
2. Investing in public transport systems and cycling infrastructure to reduce the number of private car journeys, since buses and trains carry many passengers per unit of fuel consumed, dramatically lowering per-person emissions. [1]

(e) Why developing countries may find it more difficult than developed countries to reduce greenhouse gas emissions [4]

1. Economic dependence on fossil fuels: Developing countries may depend on fossil fuels for economic growth and industrialisation, and may not be able to afford the large capital investment required to transition to cleaner technologies such as solar farms, wind turbines, and electric vehicle infrastructure. [1]
2. Lack of infrastructure and expertise: They may lack the technical infrastructure, trained personnel, and institutional capacity needed to develop, install, and maintain renewable energy systems and energy-efficient industries. [1]
3. Rapid population growth: Rapid population growth in many developing countries increases total energy demand, making it difficult to reduce absolute emissions even when efficiency improvements are made, because total consumption rises faster than per-unit savings. [1]
4. Historical responsibility argument: Developing countries may argue that developed countries, which have historically produced the vast majority of cumulative emissions through decades of industrialisation, should bear a greater responsibility and financial burden for emission reductions, making them reluctant to accept binding targets. [1]