GHG emissions are generated by our production, drilling and well test activities. We have also incorporated seismic acquisition activities in our data this year. These emissions contribute to the total atmospheric GHG emissions, which impact climate change. GHG emissions include Carbon Dioxide (CO2) and Methane (CH4).This year in line with industry guidance we are reporting annual emissions as the CO2 equivalent (CO2e) of each GHG. CO2e emissions increased 367% in 2011. CO2 emissions for the Group have increased by 361% between 2010 and 2011. CH4 emissions have increased by 420% during 2011. The key reason for this is the first full year of production and resultant flaring during the year in Ghana. In March 2012, we introduced a GHG Standard as part of toes. The objective of this new standard is to promote the efficient and responsible use of energy resources throughout Tullow operations.The conversion factor used to give methane in terms of CO2e is 21.CO2e figures have not been assured by Deloitte, however figures for CO2 and CH4 emissions have been assured.In 2011, GHG emissions (CO2e) per tonne of hydrocarbon produced increased 32%. The most significant contributor was increased production in Ghana and the need to flare additional gas. During the year, we continued to stabilise FPSO plant and processes in the Jubilee field, offshore Ghana. These hydrocarbons are defined as light sweet crude and have a relatively high gaseous content in the oil. As a result gas injection compression facilities are required to enable this gas to be re-injected into the reservoir, as this is the only available gas disposal route at this time. While the gas reinjection system was commissioned in the first half of 2011, technical issues arose in what is a complex engineering process. We have worked hard to resolve these issues and have made very good progress towards achieving the optimum level of 97.5% gas reinjection, with reinjection rates consistently exceeding 90% since the beginning of 2012. The long-term plan is that there will be no continuous flaring of hydrocarbons during normal operations.Total CO2e per thousand tonnes hydrocarbon produced is calculated as: Tonnes CO2 per thousand tonnes hydrocarbon produced plus 21x tonnes CH4 per thousand tonnes hydrocarbon produced.CO2e figures have not been assured by Deloitte, however figures for CO2 and CH4 per thousand tonnes hydrocarbon produced have been assured.2011 environmental performanceDuring the year we simplified our environmental data collation methodology and formalised the adoption of industry recognised standards for environmental data reporting. Data is monitored on a quarterly basis at Group level by the corporate EHS team. We assure Group-level performance data through Deloitte.For 2011, we have reported data for our production and drilling operations in Ghana, the UK, Uganda, Bangladesh, Pakistan and French Guiana. We also began monitoring our seismic programme environmental data this year, which included seismic acquisition campaigns in Kenya, Mauritania and Madagascar. Data has been collected for the following parameters: atmospheric emissions, water usage and spills. In the 2010 Corporate Responsibility Report we highlighted that waste management is a challenging issue for us, particularly in remote sites in isolated parts of the world. We have therefore incorporated our waste data into our environmental performance data review for 2011. One of our 2012 environmental objectives is to develop a Group position on waste management. Greenhouse gas (GHG) emissions 1,376,590 TONNES0300,000600,000900,0001,200,0001,500,00007080910112010: 294,732 TONNES294,73287,047241,056CO2CH4 as CO2e197,6031,376,590Greenhouse gas emissions per 1,000 tonnes hydrocarbon produced260.98 TONNES05010015020025007080910112010: 197.53 TONNES260.98CO2CH4 as CO2e197.5390.189.42127.5764Tullow Oil plc 2011/2012 Corporate Responsibility ReportEnvironment, Health & Safety continued

We did not achieve our Uncontrolled Releases KPI, which was introduced in 2011. This indicator measures the number and volume of spills, or unintended releases, of any materials which could impact the environment. The effect of Uncontrolled Releases to the environment depends on two components - the volume released and the receiving environment. In 2011, Tullow had 14 incidents of uncontrolled releases, which was over four times our target. Eight incidents were in Uganda and six in Ghana. While none of the incidents were particularly significant, they do demonstrate that spills need to be a key area of focus for the business, specifically drilling fluid storage and management. The EHS and Well Engineering Teams have developed a Drilling Fluids and Cuttings Disposal Standard and a set of guidelines that our operations must comply with. During 2011, we also significantly improved the reporting of environmental incidents, which will help us to enhance our processes and the integrity of our equipment.Waste is a new reporting parameter for Tullow in 2011. Effective waste management is an important aspect of operational efficiency to reduce the environmental, social and economic impacts of our activities. Waste management is a challenging issue in remote locations with limited or no infrastructure for waste disposal. Tullow operations produced 32,707 tonnes of waste in 2011, over 84% of which has been reused, recycled or treated. The most significant contributor to our waste tonnage was our Ugandan activities, which accounted for almost 80% of total Group waste. We had been storing drill cuttings onsite until we could identify approved waste contractors in the country who could legally and responsibly deal with our waste. In 2011, we were able to work with local suppliers to dispose of a considerable volume of waste. One of our environmental objectives this year is to develop a Group position on waste management. Water management is important in any area where fresh water, in particular, is constrained due to limited supply or extensive water needs. Water availability can impact the local environment and influence socio-economic activity. In 2011, we have reported the use of both fresh and seawater in our operations. Fresh water accounted for 1% and seawater 99%. We have seen a significant increase in water usage during 2011, attributable to the start-up of production in Ghana. The water reinjection system in these operations uses a significant amount of seawater, and this has accounted for almost 99% of our total water usage. The Uganda and French Guiana drilling programmes used 86,667 m3 and 18,916 m3 respectively. Although relatively small, this represents a significant increase in the use of water in Uganda. During 2011, there were five operational camps and 12 well sites, compared with three operational camps and seven well sites in 2010. We are concerned about the increase in water usage in Uganda and Kenya as our activities expand in these countries, and in 2012 we are developing a position on the issue. Waste 32,707 TONNES84.29% RECYCLED100%(waste)84.29%(recycled)Oil and chemical spills 140369121507080910112010: 4144561Water usage10,408,240m32010: 107,423m3Fresh water 1% Seawater 99% More information PageAssurance 80Supplementary EHS data 8165www.tullowoil.comMEASURING OUR PERFORMANCE3