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IB ESS Past Papers & Drilling (Paper 1): Case Study Data, Carbon and Valuation
TUTORZONE ORIGINAL DRILLING MOCK · IB ENVIRONMENTAL SYSTEMS AND SOCIETIES (ESS) PAPER 1 CASE STUDY
Written to the official IB ESS subject brief (first assessment 2026): Paper 1 uses data from a previously unseen case study and all questions are compulsory; 1 hour and 25% at SL, 2 hours and 30% at HL, with the internal assessment worth 25% at SL and 20% at HL. This mock adds an invented case study, step-by-step calculations and HL lens extensions.
What is in IB ESS and what does Paper 1 carry?
Direct answer: ESS is offered at SL and HL: Paper 1 presents data from a previously unseen case study with all questions compulsory – 1 hour and 25% at SL, 2 hours and 30% at HL; Paper 2 has short-answer and data questions in Section A and structured essays in Section B – 2 hours and 50% at SL, 2.5 hours and 50% at HL; and the internal assessment is 25% at SL and 20% at HL.
Assessment at a glance (2027)
| Component | Content | Weighting | Duration |
|---|---|---|---|
| Paper 1 (case study data analysis) | all questions compulsory: analyse and evaluate the case-study data; 1 hour and 25% at SL, 2 hours and 30% at HL | SL 25% / HL 30% | SL 1 h / HL 2 h |
| Paper 2 (short answer and structured essays) | Section A short-answer and data questions, all compulsory; Section B structured essays with a limited choice; 2 hours at SL and 2.5 at HL, 50% at both | 50% (SL/HL) | SL 2 h / HL 2.5 h |
Paper 1 technique: with a case study, first copy out the key figures (area, rates, concentrations, prices), then calculate and always give units. Evaluation answers should cover ecological, economic and social dimensions and quote the data. At SL allow about 1.5 minutes per mark; at HL the material is longer, so skim it before answering. HL candidates should be ready with the three lenses: environmental law (compensation and regulation), environmental economics (PES, carbon pricing, externalities) and environmental ethics.
How this paper was built
This is a TutorZone original drilling mock: the questions follow the IB ESS Paper 1 format (data from a previously unseen case study with all questions compulsory) and the answers are our own, not IB past papers or markschemes.
The case study and data were invented for drilling and are not a real case; the brief does not publish the marks for individual parts, so the split here is a drilling arrangement. Every numeric answer was recomputed programmatically.
Pacing
| Section | Marks | Suggested time | What to do first |
|---|---|---|---|
| Paper 1 (case study data analysis) | SL 25% / HL 30% | about 1.5 min per mark at SL | copy the data, then calculate and evaluate |
| Paper 2 (short answer and structured essays) | 50% (SL/HL) | about 50 min on Section A | clear Section A first, keep half the time for essays |
How are carbon storage and the loss period calculated?
Direct answer: total sequestration = 12,000 x 3.2 = 38,400 tonnes of carbon a year; complete loss takes 12,000 / 480 = 25.0 years; and services are worth 12,000 x 8400 = 100,800,000 a year, which is 2.4 times aquaculture revenue.
Paper 1: case-study drilling (4 parts, 40 marks)
Four parts worth 40 marks: describing trends 6, calculations 10, calculation and explanation 9 and evaluation 15. Allow 60 minutes at SL and 90 at HL.
Question 1 (40 marks)
Paper 1: case-study data analysis (invented case study)
Source: a coastal mangrove wetland covers 12,000 hectares and sequesters 3.2 tonnes of carbon per hectare a year, while 480 hectares are lost each year to aquaculture and construction. Nitrate entering the wetland is 42.0 mg per litre and leaving it 12.6 mg per litre. Ecosystem services are valued at 8400 per hectare a year against aquaculture revenue of 42 million a year. Carbon credits trade at 45 per tonne of carbon; tourism brings in 3.6 million a year and fishing 1.2 million.
(a) Describe two trends shown by the data. (6 marks)
(b) Calculate (i) the wetland’s total annual carbon sequestration, (ii) the number of years before the wetland disappears at the present rate of loss and (iii) the total value of ecosystem services as a multiple of aquaculture revenue. (10 marks)
(c) Calculate the nitrate removal rate and explain the role of wetlands in water quality management. (9 marks)
(d) Evaluate the proposal that converting the wetland to aquaculture would raise economic output. (15 marks)
HL lens extension drills (2 questions, 6 marks each, not part of the 40 marks)
The environmental economics and environmental law lenses; SL candidates can use them as extension practice. Allow 12 minutes.
Question 1 (6 marks)
Extension Question 1 (HL lens): environmental economics (6 marks, not part of the 40 marks)
Carbon credits trade at 45 per tonne of carbon and a hectare sequesters 3.2 tonnes a year. Calculate the annual carbon credit value per hectare and state one design feature of a payment for ecosystem services (PES) scheme.
Question 2 (6 marks)
Extension Question 2 (HL lens): environmental law and ethics (6 marks, not part of the 40 marks)
Local law requires 2 hectares of new wetland for every hectare of wetland filled. If 480 hectares are developed, calculate the compensation area required and state one limitation of this net-gain principle.
How are the ecological deficit and carbon budget calculated?
Direct answer: ecological deficit = 1.8 – 1.6 = 0.2 global hectares per person (an overshoot of 12.5%); the carbon budget lasts 500 / 40 = 12.5 years; and the population doubles in 70 / 0.9 = about 77.8 years, reaching about 10.6 billion in 30 years.
Paper 1 model answers
Question 1
(a) Two trends: the wetland is shrinking – 480 hectares lost a year means 12,000 / 480 = 25 years to complete loss on this trend – while it delivers high-value services including carbon storage, nitrate removal (42.0 down to 12.6 mg per litre) and tourism and fisheries income, so ecological and economic value coexist. (6 marks)
(b)(i) Total sequestration = 12,000 x 3.2 = 38,400 tonnes of carbon a year; (ii) complete loss takes 12,000 / 480 = 25.0 years; (iii) services are worth 12,000 x 8400 = 100,800,000 a year, which is 100,800,000 / 42,000,000 = 2.4 times aquaculture revenue. (10 marks)
(c) Removal rate = (42.0 – 12.6) / 42.0 x 100 = 70.0%. Wetlands take up, trap and denitrify nitrate through plants, sediment and micro-organisms, which reduces downstream algal blooms and oxygen depletion; reclaiming the wetland would mean building treatment works instead, at higher cost. (9 marks)
(d) Evaluation: for conversion, aquaculture creates jobs and export earnings with clear short-term revenue; against, the services are worth 2.4 times as much, sequestration of 38,400 tonnes a year is worth 144 per hectare in carbon credits, tourism is 3.0 times fishing income, and once the wetland is filled the loss is hard to reverse, along with flood protection, nurseries and biodiversity. Conclusion: conversion could only be justified if service values were understated and offset by restoration or compensation elsewhere; on these data, keeping the wetland has higher total value. (15 marks)
HL lens answers
Question 1
Carbon credit value = 3.2 x 45 = 144 per hectare a year. A PES design feature: payments should be tied to a measurable service such as carbon stored or water quality improved, with monitoring, verification and default provisions so that money reaches the land users who actually supply the service.
Question 2
Compensation area = 480 x 2 = 960 hectares. Limitation: new wetland takes decades to develop the functions of mature mangrove (nursery habitat, flood protection), so replacement is rarely equivalent; compensation may also sit away from the original ecological corridors or simply shift the damage elsewhere.
How should the time be allocated?
Direct answer: 60 minutes for 40 marks at SL (about 1.5 minutes per mark): 6 minutes describing, 15 calculating, 14 explaining and 22 evaluating; at HL use 90 minutes and keep 5 minutes to check.
Where these marks are usually lost
| Mistake | What it looks like | What it costs | Instead |
|---|---|---|---|
| Sequestration divided instead of multiplied | Writing 12,000 / 3.2 | The total is area x rate | 38,400 tonnes of carbon a year |
| Loss period inverted | Using 480 / 12,000 | Years = area / annual loss | 25.0 years |
| Multiple reported as a percentage | Writing 2.4 as 2.4% | A multiple is a division of totals | 2.4 times |
| Removal rate over the outflow | Using 12.6 as the denominator | The removal rate uses the inflow of 42.0 | 70.0% |
| Evaluation limited to revenue | Ignoring carbon, flood protection and biodiversity | Compare service value with development income | services worth 2.4 times aquaculture |
How to use this paper
First drill: all four parts in 60 minutes (SL) or 90 (HL).
Mark it: check every unit and denominator and confirm the evaluation covers all three dimensions.
Second drill: redo three to seven days later and test yourself with the HL lens extensions on regulation and economics.
What should I do after drilling this paper?
Direct answer: log the calculations where units or denominators went wrong, redo the paper in three to seven days, then drill Paper 2 data and essay questions and start framing your internal assessment question.
FAQ
Is this an IB past paper?
No. This is not an IB past paper: the case study, data and answers are TutorZone originals, not a markscheme.
What is in IB ESS Paper 1?
Data in a variety of forms from a previously unseen case study, with questions on analysis and evaluation; all questions are compulsory. It is 1 hour and 25% at SL, 2 hours and 30% at HL.
How do SL and HL differ?
HL has an extra hour on Paper 1, half an hour more on Paper 2 and adds three lenses (environmental law, environmental economics and environmental ethics); the internal assessment falls from 25% to 20%.
Do I need to prepare the internal assessment?
Yes. It is worth 25% at SL and 20% at HL, requires your own research question and a report of up to 3,000 words, so it needs time alongside paper drilling.
Official references
| Resource | What to check |
|---|---|
| IB ESS subject brief (first assessment 2026) | Confirm the times, weightings, internal assessment and HL lenses |
| IB official ESS curriculum page | Check the syllabus topics and assessment model |
| https://www.tutorzone.com.hk/en-ib-ess-paper-2-mock-2027/ | IB ESS Paper 2 short answer and essay drilling mock |
Related: practice area · IB ESS Paper 2 drilling mock
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